def gaia_default_dr(dr=None):
    """
    Check if dr argument is provided, if none then use default

    :param dr: Gaia DR
    :type dr: Union[NoneType, int]
    :return: Gaia DR
    :rtype: int
    :History: 2017-Oct-26 - Written - Henry Leung (University of Toronto)
    """
    if dr is None:
        dr = 1
        print(f'dr is not provided, using default dr={dr}')
    else:
        pass
    return dr
