code: def _read_json_file(self):
          
          with open(self.json_uri) as metadata_file:
              try:
                  metadata = json.load(metadata_file)
                  return metadata
              except ValueError:
                  message = tr('the file %s does not appear to be valid JSON')
                  message = message % self.json_uri
                  raise MetadataReadError(message)
docs: read metadata from a json file.
  
          :return: the parsed json dict
          :rtype: dict