def METHOD_NAME(self):
    G1 = Gf(mesh=self.iw_mesh, target_shape=(2,2))
    G2 = G1.copy()
    G1 << inverse(2 + iOmega_n)
    G2 << inverse(2 - iOmega_n)
    B1 = BlockGf(name_list=['0', '1'], block_list=[G1, G2])
    B2 = BlockGf(name_list=['0', '1'], block_list=[G2, G1])
    assert_block_gfs_are_close(-B1.imag, B2.imag)