from datetime import datetime, timedelta
from collections import Counter


def date_range(start, end):
    if isinstance(start, datetime):
        start = start.date()
    if isinstance(end, datetime):
        end = end.date()
    delta = end - start
    for d in range(delta.days + 1):
        yield start + timedelta(days=d)
    return


def weekdays_in_date_range(start, end):
    return Counter([d.isoweekday() for d in date_range(start, end)])


def dates_overlap(start, end, start2, end2):
    return start <= end2 and start2 <= end