def union(mask_a, mask_b):
    '\n    This function ...\n    :param args:\n    :return:\n    '
    return (mask_a + mask_b)
This function ...
:param args:
:return:
def union(mask_a, mask_b):
    '\n    This function ...\n    :param args:\n    :return:\n    '
    return (mask_a + mask_b)