import re


def check_date_format(date_str):
    """ Check the date to ensure that it's in the proper format
    """
    pattern = re.compile("^\d{4}-+\d{2}-+\d{2}T+\d{2}:+\d{2}:+\d{2}.+\d{1,}Z+$")
    matched = pattern.match(date_str)
    return matched