docs: def _ConvertToCanonicalSqlDict(self, schema, raw_dict, prefix=""):
      """Converts a dict of RDF values into a SQL-ready form."""
      flattened_dict = {}
      for k, v in iteritems(raw_dict):
        if isinstance(v, dict):
          flattened_dict.update(
              self._ConvertToCanonicalSqlDict(
                  schema, v, prefix="%s%s." % (prefix, k)))
        else:
          field_name = prefix + k
          flattened_dict[field_name] = schema[field_name].convert_fn(v)
      return flattened_dict