<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _prepend_schema_name(self, message):
 """ If a custom schema name has been defined, prepends it to the error message that gets raised when a schema error occurs. """

        if self._name:
            message = "{0!r} {1!s}".format(self._name, message)
        return message