(id_map1, id_map2)
return merge_table.map(lambda k, v: (v[0], v[1]))
:param id_map1: (a, b)
        :param id_map2: (a, c)
        :return: (c, b)
def _merge(id_map1, id_map2):
        """

        :param id_map1: (a, b)
        :param id_map2: (a, c)
        :return: (c, b)
        """
        merge_table = id_map1.join(id_map2, lambda v, u: (u, v))
        return merge_table.map(lambda k, v: (v[0], v[1]))
def _merge ( id_map1 , id_map2 ) : merge_table = id_map1 . join ( id_map2 , lambda v , u : ( u , v ) ) return merge_table . map ( lambda k , v : ( v [ 0 ] , v [ 1 ] ) )