Fetches all messages in the database.

        :rtype: Generator[can.Message]

def read_all(self):
        """Fetches all messages in the database.

        :rtype: Generator[can.Message]
        """
        result = self._cursor.execute("SELECT * FROM {}".format(self.table_name)).fetchall()
        return (SqliteReader._assemble_message(frame) for frame in result)