Stuff to do with counters, sequences and iterables.

Latest release 20260912: Small doc update.

Note that any function accepting an iterable will consume some or all of the derived iterator in the course of its function.

Short summary:

• ClonedIterator: OBSOLETE version of ReIterable.

• common_prefix_length: Return the length of the common prefix of sequences seqs.

• common_suffix_length: Return the length of the common suffix of sequences seqs.

• consume: Consume the iterator it. If last_item(item) is true for some item from the iterator, cease at that item; the default last_item returns False, consuming everything from the iterator. Return the last item consumed, or no_items (default None) if there were no items.

• consumed: Consume the iterator it, a variation on consume(). If last_item(item) is true for some item from the iterator, cease at that item; the default last_item returns False, consuming everything from the iterator. Return an iterator yielding the last item consumed (if any) and then the remaining items from it.

• first: Return the first item from an iterable; raise IndexError on empty iterables.

• get0: Return first element of an iterable, or the default.

• greedy: A decorator or function for greedy computation of iterables.

• imerge: Merge an iterable of ordered iterables in order.

• infill: A generator accepting an iterable of objects which yields (obj,missing_keys) 2-tuples indicating missing records requiring infill for each object.

• infill_from_batches: A batched version of infill(objs) accepting an iterable of batches of objects which yields (obj,obj_key) 2-tuples indicating missing records requiring infill for each object.

• isordered: Test whether an iterable is ordered. Note that the iterable is iterated, so this is a destructive test for nonsequences.

• last: Return the last item from an iterable; raise IndexError on empty iterables.

• not_none: Filter the iterables for items which are not None.

• onetomany: A decorator for a method of a sequence to merge the results of passing every element of the sequence to the function, expecting multiple values back.

• onetoone: A decorator for a method of a sequence to merge the results of passing every element of the sequence to the function, expecting a single value back.

• order: A convenience wrapper for an Ordered instance to order the indexed_items.

• Ordered: A class to yield indexed but out of order values in index order such as you may receive from completion of concurrent actions which you want to process in submission order but otherwise as soon as possible.

• range: A class like the builtin range exceppt that it will accept ... as the stop value, indicating an unbound range. Note that if initialised like a normal range it returns a builtin range instance.

• ReIterable: A thread safe clone of some orginal iterator.

• Seq: A numeric sequence implemented as a thread safe wrapper for itertools.count().

• seq: Return a new sequential value.

• skip_map: A version of map() which will skip items where func(item) raises an exception in except_types, a tuple of exception types. If a skipped exception occurs a warning will be issued unless quiet is true (default False).

• splitoff: Split a sequence into (usually short) prefixes and a tail, for example to construct subdirectory trees based on a UUID.

• StatefulIterator: A trivial iterator which wraps another iterator to expose some tracking state.

• tee: A generator yielding the items from an iterable which also copies those items to a series of queues.

• the: Returns the first element of an iterable, but requires there to be exactly one.

• TrackingCounter: A wrapper for a counter which can be incremented and decremented.

• unrepeated: A generator yielding items from the iterable it with no repetitions.

• with_neighbours: Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

Functions

ClonedIterator(it: Iterable, no_neighbour=None)

OBSOLETE version of ReIterable

A thread safe clone of some orginal iterator.

next() of this yields the next item from the supplied iterator. iter() of this returns a generator yielding from the historic items and then from the original iterator.

Note that this accrues all of the items from the original iterator in memory.

common_prefix_length(it: Iterable, no_neighbour=None)

Return the length of the common prefix of sequences seqs.

common_suffix_length(it: Iterable, no_neighbour=None)

Return the length of the common suffix of sequences seqs.

consume(it: Iterable, no_neighbour=None)

Consume the iterator it. If last_item(item) is true for some item from the iterator, cease at that item; the default last_item returns False, consuming everything from the iterator. Return the last item consumed, or no_items (default None) if there were no items.

consumed(it: Iterable, no_neighbour=None)

Consume the iterator it, a variation on consume(). If last_item(item) is true for some item from the iterator, cease at that item; the default last_item returns False, consuming everything from the iterator. Return an iterator yielding the last item consumed (if any) and then the remaining items from it.

first(it: Iterable, no_neighbour=None)

Return the first item from an iterable; raise IndexError on empty iterables.

get0(it: Iterable, no_neighbour=None)

Return first element of an iterable, or the default.

greedy(it: Iterable, no_neighbour=None)

A decorator or function for greedy computation of iterables.

If g is omitted or callable this is a decorator for a generator function causing it to compute greedily, capacity limited by queue_depth.

If g is iterable this function dispatches it in a Thread to compute greedily, capacity limited by queue_depth.

Example with an iterable:

for packet in greedy(parse_data_stream(stream)):
    ... process packet ...

which does some readahead of the stream.

Example as a function decorator:

@greedy
def g(n):
    for item in range(n):
        yield n

This can also be used directly on an existing iterable:

for item in greedy(range(n)):
    yield n

Normally a generator runs on demand. This function dispatches a Thread to run the iterable (typically a generator) putting yielded values to a queue and returns a new generator yielding from the queue.

The queue_depth parameter specifies the depth of the queue and therefore how many values the original generator can compute before blocking at the queue's capacity.

The default queue_depth is 0 which creates a Channel as the queue - a zero storage buffer - which lets the generator compute only a single value ahead of time.

A larger queue_depth allocates a Queue with that much storage allowing the generator to compute as many as queue_depth+1 values ahead of time.

Here's a comparison of the behaviour:

Example without @greedy where the "yield 1" step does not occur until after the "got 0":

>>> from time import sleep
>>> def g():
...   for i in range(2):
...     print("yield", i)
...     yield i
...   print("g done")
...
>>> G = g(); sleep(0.1)
>>> for i in G:
...   print("got", i)
...   sleep(0.1)
...
yield 0
got 0
yield 1
got 1
g done

Example with @greedy where the "yield 1" step computes before the "got 0":

>>> from time import sleep
>>> @greedy
... def g():
...   for i in range(2):
...     print("yield", i)
...     yield i
...   print("g done")
...
>>> G = g(); sleep(0.1)
yield 0
>>> for i in G:
...   print("got", repr(i))
...   sleep(0.1)
...
yield 1
got 0
g done
got 1

Example with @greedy(queue_depth=1) where the "yield 1" step computes before the "got 0":

>>> from cs.x import X
>>> from time import sleep
>>> @greedy
... def g():
...   for i in range(3):
...     X("Y")
...     print("yield", i)
...     yield i
...   print("g done")
...
>>> G = g(); sleep(2)
yield 0
yield 1
>>> for i in G:
...   print("got", repr(i))
...   sleep(0.1)
...
yield 2
got 0
yield 3
got 1
g done
got 2

imerge(it: Iterable, no_neighbour=None)

Merge an iterable of ordered iterables in order.

Parameters:

• iters: an iterable of iterators
• reverse: keyword parameter: if true, yield items in reverse order. This requires the iterables themselves to also be in reversed order.

This function relies on the source iterables being ordered and their elements being comparable, through slightly misordered iterables (for example, as extracted from web server logs) will produce only slightly misordered results, as the merging is done on the basis of the front elements of each iterable.

infill(it: Iterable, no_neighbour=None)

A generator accepting an iterable of objects which yields (obj,missing_keys) 2-tuples indicating missing records requiring infill for each object.

Parameters:

• objs: an iterable of objects
• obj_keys: a callable accepting an object and returning an iterable of the expected keys
• existsing_keys: a callable accepting an object and returning an iterable of the existing keys
• all: optional flag, default False: if true then yield (obj,()) for objects with no missing records

Example:

for obj, missing_key in infill(objs,...):
  ... infill a record for missing_key ...

infill_from_batches(it: Iterable, no_neighbour=None)

A batched version of infill(objs) accepting an iterable of batches of objects which yields (obj,obj_key) 2-tuples indicating missing records requiring infill for each object.

This is aimed at processing batches of objects where it is more efficient to prepare each batch as a whole, such as a Django QuerySet which lets the caller make single database queries for a batch of Model instances. Thus this function can be used with cs.djutils.model_batches_qs for more efficient infill processing.

Parameters:

• objss: an iterable of iterables of objects
• obj_keys: a callable accepting an object and returning an iterable of the expected keys
• existsing_keys: a callable accepting an object and returning an iterable of the existing keys
• all: optional flag, default False: if true then yield (obj,()) for objects with no missing records
• amend_batch: optional callable to amend the batch of objects, for example to amend a QuerySet with .select_related() or similar

isordered(it: Iterable, no_neighbour=None)

Test whether an iterable is ordered. Note that the iterable is iterated, so this is a destructive test for nonsequences.

last(it: Iterable, no_neighbour=None)

Return the last item from an iterable; raise IndexError on empty iterables.

not_none(it: Iterable, no_neighbour=None)

Filter the iterables for items which are not None.

onetomany(it: Iterable, no_neighbour=None)

A decorator for a method of a sequence to merge the results of passing every element of the sequence to the function, expecting multiple values back.

Example:

  class X(list):
        @onetomany
        def chars(self, item):
              return item
  strs = X(['Abc', 'Def'])
  all_chars = X.chars()

onetoone(it: Iterable, no_neighbour=None)

A decorator for a method of a sequence to merge the results of passing every element of the sequence to the function, expecting a single value back.

Example:

  class X(list):
        @onetoone
        def lower(self, item):
              return item.lower()
  strs = X(['Abc', 'Def'])
  lower_strs = X.lower()

order(it: Iterable, no_neighbour=None)

A convenience wrapper for an Ordered instance to order the indexed_items.

Example:

>>> # an iterator yielding unordered results, just because
>>> unordered_results = iter( ((2, "third"), (0, "first"), (1, "second")) )
>>> for i, result in order(unordered_results):
...   print(i, result)
...
0 first
1 second
2 third

seq(it: Iterable, no_neighbour=None)

Return a new sequential value.

skip_map(it: Iterable, no_neighbour=None)

A version of map() which will skip items where func(item) raises an exception in except_types, a tuple of exception types. If a skipped exception occurs a warning will be issued unless quiet is true (default False).

splitoff(it: Iterable, no_neighbour=None)

Split a sequence into (usually short) prefixes and a tail, for example to construct subdirectory trees based on a UUID.

Example:

>>> from uuid import UUID
>>> uuid = 'd6d9c510-785c-468c-9aa4-b7bda343fb79'
>>> uu = UUID(uuid).hex
>>> uu
'd6d9c510785c468c9aa4b7bda343fb79'
>>> splitoff(uu, 2, 2)
['d6', 'd9', 'c510785c468c9aa4b7bda343fb79']

tee(it: Iterable, no_neighbour=None)

A generator yielding the items from an iterable which also copies those items to a series of queues.

Parameters:

• iterable: the iterable to copy
• Qs: the queues, objects accepting a .put method.

Note: the item is .put onto every queue before being yielded from this generator.

the(it: Iterable, no_neighbour=None)

Returns the first element of an iterable, but requires there to be exactly one.

unrepeated(it: Iterable, no_neighbour=None)

A generator yielding items from the iterable it with no repetitions.

Parameters:

• it: the iterable to process
• seen: an optional setlike container supporting in and .add()
• signature: an optional signature function for items from it which produces the value to compare to recognise repeated items; its values are stored in the seen set

The default signature function is equality; the items are stored n seen and compared. This requires the items to be hashable and support equality tests. The same applies to whatever values the signature function produces.

Another common signature is identity: id, useful for traversing a graph which may have cycles.

Since seen accrues all the signature values for yielded items generally it will grow monotonicly as iteration proceeeds. If the items are complex or large it is well worth providing a signature function even if the items themselves can be used in a set.

with_neighbours(it: Iterable, no_neighbour=None)

Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

The first item will have a prev of no_neighbour and the last item will have a next of no_neighbour.

no_neighbour defaults to None, but may be specified as another sentinel if None is anticipated in the iterable.

Examples:

>>> list(with_neighbours((1,2,3)))
[(None, 1, 2), (1, 2, 3), (2, 3, None)]
>>> list(with_neighbours(()))
[]
>>> list(with_neighbours((1,)))
[(None, 1, None)]
>>> list(with_neighbours((1,2)))
[(None, 1, 2), (1, 2, None)]
>>> list(with_neighbours((1,None,3),"END"))
[('END', 1, None), (1, None, 3), (None, 3, 'END')]

Classes

class Ordered

Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

The first item will have a prev of no_neighbour and the last item will have a next of no_neighbour.

no_neighbour defaults to None, but may be specified as another sentinel if None is anticipated in the iterable.

Examples:

>>> list(with_neighbours((1,2,3)))
[(None, 1, 2), (1, 2, 3), (2, 3, None)]
>>> list(with_neighbours(()))
[]
>>> list(with_neighbours((1,)))
[(None, 1, None)]
>>> list(with_neighbours((1,2)))
[(None, 1, 2), (1, 2, None)]
>>> list(with_neighbours((1,None,3),"END"))
[('END', 1, None), (1, None, 3), (None, 3, 'END')]

####Ordered.__dict__

Read-only proxy of a mapping.

####Ordered.__firstlineno__

int([x]) -> integer int(x, base=10) -> integer

Convert a number or string to an integer, or return 0 if no arguments are given. If x is a number, return x.int(). For floating-point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal.

int('0b100', base=0) 4

####Ordered.__static_attributes__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

Ordered.drain(self) -> Generator[Tuple[cs.typingutils.Sortable, Any], NoneType, NoneType]

A generator yielding (index,value) 2-tuples from the heap until it is empty.

Ordered.push(self, index, value) -> Generator[Tuple[cs.typingutils.Sortable, Any], NoneType, NoneType]

A generator to push an (index,value) 2-tuple onto the heap and then yield (index,value) 2-tuples from the heap while it is not empty and the top element equals the expected next index from self.indices.

class ReIterable(collections.abc.Iterable, typing.Generic)

Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

The first item will have a prev of no_neighbour and the last item will have a next of no_neighbour.

no_neighbour defaults to None, but may be specified as another sentinel if None is anticipated in the iterable.

Examples:

>>> list(with_neighbours((1,2,3)))
[(None, 1, 2), (1, 2, 3), (2, 3, None)]
>>> list(with_neighbours(()))
[]
>>> list(with_neighbours((1,)))
[(None, 1, None)]
>>> list(with_neighbours((1,2)))
[(None, 1, 2), (1, 2, None)]
>>> list(with_neighbours((1,None,3),"END"))
[('END', 1, None), (1, None, 3), (None, 3, 'END')]

ReIterable.__init__(self, it: Iterable)

Initialise the clone with the iterable it.

####ReIterable.__annotations__

dict() -> new empty dictionary dict(mapping) -> new dictionary initialized from a mapping object's (key, value) pairs dict(iterable) -> new dictionary initialized as if via: d = {} for k, v in iterable: d[k] = v dict(**kwargs) -> new dictionary initialized with the name=value pairs in the keyword argument list. For example: dict(one=1, two=2)

####ReIterable.__dict__

Read-only proxy of a mapping.

####ReIterable.__firstlineno__

int([x]) -> integer int(x, base=10) -> integer

Convert a number or string to an integer, or return 0 if no arguments are given. If x is a number, return x.int(). For floating-point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal.

int('0b100', base=0) 4

ReIterable.__iter__(self)

Iterate over the clone, returning a new iterator.

In mild violation of the iterator protocol, instead of returning self, iter(self) returns a generator yielding the historic and then current contents of the original iterator.

ReIterable.__next__(self)

Return the next item from the original iterator.

####ReIterable.__orig_bases__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

####ReIterable.__parameters__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

####ReIterable.__static_attributes__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

class Seq

Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

The first item will have a prev of no_neighbour and the last item will have a next of no_neighbour.

no_neighbour defaults to None, but may be specified as another sentinel if None is anticipated in the iterable.

Examples:

>>> list(with_neighbours((1,2,3)))
[(None, 1, 2), (1, 2, 3), (2, 3, None)]
>>> list(with_neighbours(()))
[]
>>> list(with_neighbours((1,)))
[(None, 1, None)]
>>> list(with_neighbours((1,2)))
[(None, 1, 2), (1, 2, None)]
>>> list(with_neighbours((1,None,3),"END"))
[('END', 1, None), (1, None, 3), (None, 3, 'END')]

####Seq.__firstlineno__

int([x]) -> integer int(x, base=10) -> integer

Convert a number or string to an integer, or return 0 if no arguments are given. If x is a number, return x.int(). For floating-point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal.

int('0b100', base=0) 4

####Seq.__slots__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

####Seq.__static_attributes__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

class StatefulIterator

Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

The first item will have a prev of no_neighbour and the last item will have a next of no_neighbour.

no_neighbour defaults to None, but may be specified as another sentinel if None is anticipated in the iterable.

Examples:

>>> list(with_neighbours((1,2,3)))
[(None, 1, 2), (1, 2, 3), (2, 3, None)]
>>> list(with_neighbours(()))
[]
>>> list(with_neighbours((1,)))
[(None, 1, None)]
>>> list(with_neighbours((1,2)))
[(None, 1, 2), (1, 2, None)]
>>> list(with_neighbours((1,None,3),"END"))
[('END', 1, None), (1, None, 3), (None, 3, 'END')]

####StatefulIterator.__dict__

Read-only proxy of a mapping.

####StatefulIterator.__firstlineno__

int([x]) -> integer int(x, base=10) -> integer

Convert a number or string to an integer, or return 0 if no arguments are given. If x is a number, return x.int(). For floating-point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal.

int('0b100', base=0) 4

####StatefulIterator.__static_attributes__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

class TrackingCounter

Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

The first item will have a prev of no_neighbour and the last item will have a next of no_neighbour.

no_neighbour defaults to None, but may be specified as another sentinel if None is anticipated in the iterable.

Examples:

>>> list(with_neighbours((1,2,3)))
[(None, 1, 2), (1, 2, 3), (2, 3, None)]
>>> list(with_neighbours(()))
[]
>>> list(with_neighbours((1,)))
[(None, 1, None)]
>>> list(with_neighbours((1,2)))
[(None, 1, 2), (1, 2, None)]
>>> list(with_neighbours((1,None,3),"END"))
[('END', 1, None), (1, None, 3), (None, 3, 'END')]

TrackingCounter.__init__(self, value=0, name=None, lock=None)

Initialise the counter to value (default 0) with the optional name.

####TrackingCounter.__dict__

Read-only proxy of a mapping.

####TrackingCounter.__firstlineno__

int([x]) -> integer int(x, base=10) -> integer

Convert a number or string to an integer, or return 0 if no arguments are given. If x is a number, return x.int(). For floating-point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal.

int('0b100', base=0) 4

####TrackingCounter.__static_attributes__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

TrackingCounter.check(self)

Internal consistency check.

TrackingCounter.dec(self, tag=None)

Decrement the counter. Wake up any threads waiting for its new value.

TrackingCounter.inc(self, tag=None)

Increment the counter. Wake up any threads waiting for its new value.

TrackingCounter.wait(self, value)

Wait for the counter to reach the specified value.

class range

Return 3-tuples of (prev,curr,next) from the iterable it where curr is each item from it and prev and next are the preceeding and following items respectively.

The first item will have a prev of no_neighbour and the last item will have a next of no_neighbour.

no_neighbour defaults to None, but may be specified as another sentinel if None is anticipated in the iterable.

Examples:

>>> list(with_neighbours((1,2,3)))
[(None, 1, 2), (1, 2, 3), (2, 3, None)]
>>> list(with_neighbours(()))
[]
>>> list(with_neighbours((1,)))
[(None, 1, None)]
>>> list(with_neighbours((1,2)))
[(None, 1, 2), (1, 2, None)]
>>> list(with_neighbours((1,None,3),"END"))
[('END', 1, None), (1, None, 3), (None, 3, 'END')]

range.__class_getitem__(index)

You can also index this range type` with a slice, obtaining a range matching the slice.

####range.__dict__

Read-only proxy of a mapping.

####range.__firstlineno__

int([x]) -> integer int(x, base=10) -> integer

Convert a number or string to an integer, or return 0 if no arguments are given. If x is a number, return x.int(). For floating-point numbers, this truncates towards zero.

If x is not a number or if base is given, then x must be a string, bytes, or bytearray instance representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal.

int('0b100', base=0) 4

####range.__static_attributes__

Built-in immutable sequence.

If no argument is given, the constructor returns an empty tuple. If iterable is specified the tuple is initialized from iterable's items.

If the argument is a tuple, the return value is the same object.

Release Log

Release 20260912: Small doc update.

Release 20260622:

• Rename ClonedIteraor to ReIterable, sugestion by λambda @ python.discord.
• New consume(Iterable) function to "run" an iterable without storing the results.
• New consumed(Iterator) returning an Iterator with the last consumed item and the tail of the original iterator.

Release 20260526: Update some type annotations for pre-Python 3.13.

Release 20260525.1: order: yield sorted indexed item, convenience wrapper for Ordered.

Release 20260525: Ordered class for pushing out of order results and yielding in order results.

Release 20260403: New generator with_neighbours(iterable) to yield (prev,curr,next) 3-tuples.

Release 20251231.1: range: support range[type] returning a GenericAlias.

Release 20251231: range: support making a range like range[1::2] for the odd numbers.

Release 20251230:

• New not_none(*iterables) generator yielding items which are not none, handy in * expansions.
• New range() class accepting ... for the stop.

Release 20250914: ClonedIterator: it may be an Iterable, not just an Iterator.

Release 20250801: ClonedIterator: bugfix direct iteration, noticed by @Matiss.

Release 20250724: New ClonedIterator class to provide a reiterable clone of an iterator.

Release 20250306: New infill() and infill_from_batches() generators for identifying missing records requiring an infill.

Release 20250103: New skip_map(func, *iterables, except_types, quiet=False) generator function, like map() but skipping certain exceptions.

Release 20221118: Small doc improvement.

Release 20220530: Seq: calling a Seq is like next(seq).

Release 20210924: New greedy(iterable) or @greedy(generator_function) to let generators precompute.

Release 20210913: New unrepeated() generator removing duplicates from an iterable.

Release 20201025: New splitoff() function to split a sequence into (usually short) prefixes and a tail.

Release 20200914: New common_prefix_length and common_suffix_length for comparing prefixes and suffixes of sequences.

Release 20190103: Documentation update.

Release 20190101:

• New and UNTESTED class StatefulIterator to associate some externally visible state with an iterator.
• Seq: accept optional lock parameter.

Release 20171231:

• Python 2 backport for imerge().
• New tee function to duplicate an iterable to queues.
• Function isordered() is now a test instead of an assertion.
• Drop NamedTuple, NamedTupleClassFactory (unused).

Release 20160918:

• New function isordered() to test ordering of a sequence.
• imerge: accept new reverse parameter for merging reversed iterables.

Release 20160828: Modify DISTINFO to say "install_requires", fixes pypi requirements.

Release 20160827: TrackingCounter: accept presupplied lock object. Python 3 exec fix.

Release 20150118: metadata update

Release 20150111: Initial PyPI release.