docs: def read_moc_json(moc, filename=None, file=None):
      """Read JSON encoded data into a MOC.
  
      Either a filename, or an open file object can be specified.
      """
  
      if file is not None:
          obj = _read_json(file)
      else:
          with open(filename, 'rb') as f:
              obj = _read_json(f)
  
      for (order, cells) in obj.items():
          moc.add(order, cells)