How to use the fastavro.io.symbols.Double function in fastavro

elif record_type == "null":
            return Null()
        elif record_type == "boolean":
            return Boolean()
        elif record_type == "string":
            return String()
        elif record_type == "bytes":
            return Bytes()
        elif record_type == "int":
            return Int()
        elif record_type == "long":
            return Long()
        elif record_type == "float":
            return Float()
        elif record_type == "double":
            return Double()
        elif record_type == "fixed":
            return Fixed()
        else:
            raise Exception("Unhandled type: {}".format(record_type))

def read_double(self):
        self._parser.advance(Double())
        return self.read_value()

def write_double(self, value):
        self._parser.advance(Double())
        self.write_value(value)