docs: def _get_mapping(self, schema):
          """Get mapping for given resource or item schema.
  
          :param schema: resource or dict/list type item schema
          """
          properties = {}
          for field, field_schema in schema.items():
              field_mapping = self._get_field_mapping(field_schema)
              if field_mapping:
                  properties[field] = field_mapping
          return {'properties': properties}