>>> layout = ts.ChunkLayout(
...     inner_order=[0, 2, 1],
...     write_chunk_shape_soft_constraint=[100, None, 200],
...     read_chunk_elements=1000000)
>>> layout.to_json()
{'inner_order': [0, 2, 1],
 'read_chunk': {'elements': 1000000},
 'write_chunk': {'shape_soft_constraint': [100, None, 200]}}