Retrieves completed assignments for a HIT. 
        Use this operation to retrieve the results for a HIT.

        The returned ResultSet will have the following attributes:

        NumResults
                The number of assignments on the page in the filtered results
                list, equivalent to the number of assignments being returned
                by this call.
                A non-negative integer
        PageNumber
                The number of the page in the filtered results list being
                returned.
                A positive integer
        TotalNumResults
                The total number of HITs in the filtered results list based
                on this call.
                A non-negative integer

        The ResultSet will contain zero or more Assignment objects

def get_assignments(self, hit_id, status=None,
                            sort_by='SubmitTime', sort_direction='Ascending', 
                            page_size=10, page_number=1, response_groups=None):
        """
        Retrieves completed assignments for a HIT. 
        Use this operation to retrieve the results for a HIT.

        The returned ResultSet will have the following attributes:

        NumResults
                The number of assignments on the page in the filtered results
                list, equivalent to the number of assignments being returned
                by this call.
                A non-negative integer
        PageNumber
                The number of the page in the filtered results list being
                returned.
                A positive integer
        TotalNumResults
                The total number of HITs in the filtered results list based
                on this call.
                A non-negative integer

        The ResultSet will contain zero or more Assignment objects 

        """
        params = {'HITId' : hit_id,
                  'SortProperty' : sort_by,
                  'SortDirection' : sort_direction,
                  'PageSize' : page_size,
                  'PageNumber' : page_number}

        if status is not None:
            params['AssignmentStatus'] = status

        # Handle optional response groups argument
        if response_groups:
            self.build_list_params(params, response_groups, 'ResponseGroup')
                
        return self._process_request('GetAssignmentsForHIT', params,
                                     [('Assignment', Assignment),])