<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _to_viewitem(self, prog_var):
 """ Convert a ProgramVariable instance to a DDGViewItem object. :param ProgramVariable prog_var: The ProgramVariable object to convert. :return: The converted DDGViewItem object. :rtype: DDGViewItem """


        return DDGViewItem(self._ddg, prog_var, simplified=self._simplified)