Days Counting is date utility functions to extend python's datetime
Extend python datetime with excel-like workday addition/subtraction functionality:
Returns the number of whole working days between from_date and to_date (inclusive of both from_date and to_date). Working days exclude weekends and any dates identified in holidays. Use COUNT_LEAVE to calculate employee benefits that accrue based on the number of days worked during a specific term.
Returns a number that represents a date that is the indicated number of working days before or after a date (the starting date). Working days exclude weekends and any dates identified as holidays. Use COUNT_WORKDAY to exclude weekends or holidays when you calculate invoice due dates, expected delivery times, or the number of days of work performed.
This module has similarities with the BusinessHours module - you may want to check it out as well to see which one better fits your needs.