<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def dependent_hosted_number_orders(self):
 """ Access the dependent_hosted_number_orders :returns: twilio.rest.preview.hosted_numbers.authorization_document.dependent_hosted_number_order.DependentHostedNumberOrderList :rtype: twilio.rest.preview.hosted_numbers.authorization_document.dependent_hosted_number_order.DependentHostedNumberOrderList """

        if self._dependent_hosted_number_orders is None:
            self._dependent_hosted_number_orders = DependentHostedNumberOrderList(
                self._version,
                signing_document_sid=self._solution['sid'],
            )
        return self._dependent_hosted_number_orders