docs: def get_prep_value(self, value):
          '''The psycopg adaptor returns Python objects,
              but we also have to handle conversion ourselves
          '''
          if isinstance(value, JSON.JsonDict):
              return json.dumps(value, cls=JSON.Encoder)
          if isinstance(value, JSON.JsonList):
              return value.json_string
          if isinstance(value, JSON.JsonString):
              return json.dumps(value)
          return value