docs: def json_description_metadata(description):
      """Return metatata from JSON formated image description as dict.
  
      Raise ValuError if description is of unknown format.
  
      >>> description = '{"shape": [256, 256, 3], "axes": "YXS"}'
      >>> json_description_metadata(description)  # doctest: +SKIP
      {'shape': [256, 256, 3], 'axes': 'YXS'}
      >>> json_description_metadata('shape=(256, 256, 3)')
      {'shape': (256, 256, 3)}
  
      """
      if description[:6] == 'shape=':
          # old-style 'shaped' description; not JSON
          shape = tuple(int(i) for i in description[7:-1].split(','))
          return dict(shape=shape)
      if description[:1] == '{' and description[-1:] == '}':
          # JSON description
          return json.loads(description)
      raise ValueError('invalid JSON image description', description)