human
I wrote the below code

    def assert_components(batch1, batch2):
        for (e1, e2) in zip(batch1, batch2):
            if (isinstance(e1, tuple) and isinstance(e2, tuple)):
                assert_components(e1, e2)
            elif (isinstance(e1, tuple) or isinstance(e2, tuple)):
                raise ValueError('Composite    batches    do    not    match.')
            else:
                assert np.allclose(e1, e2)
    VS = VectorSpace(dim=27)
    VS_sparse = VectorSpace(dim=27, sparse=True)
    VS_batch = np.arange(270).reshape(10, 27)
    new_SVS_batch = VS.np_format_as(VS_batch, VS_sparse)
    new_VS_batch = VS.undo_np_format_as(new_SVS_batch, VS_sparse)
    assert np.allclose(new_VS_batch, VS_batch)
    CS = Conv2DSpace(shape=[3, 3], num_channels=3, axes=('b', 0, 1, 'c'), dtype='float32')
    CS_non_default = Conv2DSpace(shape=[3, 3], num_channels=3, axes=('c', 'b', 0, 1), dtype='float64')
    CS_batch = np.arange(270).reshape(10, 3, 3, 3).astype('float32')
    new_ndCS_batch = CS.np_format_as(CS_batch, CS_non_default)
    new_CS_batch = CS.undo_np_format_as(new_ndCS_batch, CS_non_default)
    assert np.allclose(new_CS_batch, CS_batch)
    assert (new_ndCS_batch.shape != CS_batch.shape)
    assert (new_ndCS_batch.dtype == 'float64')
    assert (new_CS_batch.dtype == 'float32')
    ndCS_batch = np.arange(270).reshape(3, 10, 3, 3)
    new_CS_batch = CS_non_default.np_format_as(ndCS_batch, CS)
    new_ndCS_batch = CS_non_default.undo_np_format_as(new_CS_batch, CS)
    assert np.allclose(new_ndCS_batch, ndCS_batch)
    assert (new_CS_batch.shape != ndCS_batch.shape)
    assert (new_ndCS_batch.dtype == 'float64')
    assert (new_CS_batch.dtype == 'float32')
    VS_batch = np.arange(270).reshape(10, 27)
    new_CS_batch = VS.np_format_as(VS_batch, CS)
    new_VS_batch = VS.undo_np_format_as(new_CS_batch, CS)
    assert np.allclose(new_VS_batch, VS_batch)
    new_CS_batch = VS.np_format_as(VS_batch, CS_non_default)
    new_VS_batch = VS.undo_np_format_as(new_CS_batch, CS_non_default)
    assert np.allclose(new_VS_batch,...

What's a good function header?
assistant
#Here's a good function header.

def test_numeric_undo_format_as():