def is_gregorian (year, month, day):
    """ Given a date as year, month number and day number, return if
    that date is gregorian or not

    Parameters
    ----------
    year : int
        A year number
    month : [type]
        A month number 1<=month<=12
    day : [type]
        day number 1<=day<=31

    Returns
    -------
    bool
        True if the date is Gregorian. False, otherwise
    """
    if year > 1582:
        return True
    elif year < 1582 :
        return False
    elif month > 10 :
        return True
    elif month < 10 :
        return False
    else :
        return (day>=15)