<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_input_validator(self, request):
 """ Return appropriate input validator. For POST requests, ``self.post_representation`` is returned if it is present, ``self.representation`` otherwise. """


        method = request.method.upper()
        if method != 'POST':
            return self.representation
        elif self.post_representation:
            return self.post_representation
        else:
            return self.representation