code: def get_json_ld_extra(key, value):
      '''Serialize an extras key, value pair into JSON-LD'''
      value = value.serialize() if hasattr(value, 'serialize') else value
      return {
          '@type': 'http://schema.org/PropertyValue',
          'name': key,
          'value': value,
      f get_json_ld_extra(key, value):
      '''Serialize an extras key, value pair into JSON-LD'''
      value = value.serialize() if hasattr(value, 'serialize') else value
      return {
          '@type': 'http://schema.org/PropertyValue',
          'name': key,
          'value': value,
      }
docs: Serialize an extras key, value pair into JSON-LD