How to use the identify.FF_CHILDREN_COUNT function in identify

def get_measurement_columns(self, pipeline):
        '''Return information to use when creating database columns'''
        orig_image_name = self.object_name.value
        filtered_image_name = self.filtered_objects.value
        columns = I.get_object_measurement_columns(filtered_image_name)
        columns += [(orig_image_name,
                     I.FF_CHILDREN_COUNT % filtered_image_name,
                     cpmeas.COLTYPE_INTEGER),
                    (filtered_image_name,
                     I.FF_PARENT %  orig_image_name,
                     cpmeas.COLTYPE_INTEGER)]
        return columns

def get_measurement_columns(self, pipeline):
        '''Return column definitions for measurements made by this module'''
        subregion_name = self.subregion_objects_name.value
        columns = cpmi.get_object_measurement_columns(subregion_name)
        for parent in (self.primary_objects_name.value, 
                       self.secondary_objects_name.value):
            columns += [(parent,
                         cpmi.FF_CHILDREN_COUNT%subregion_name,
                         cpmeas.COLTYPE_INTEGER),
                        (subregion_name,
                         cpmi.FF_PARENT%parent,
                         cpmeas.COLTYPE_INTEGER)]
        return columns

cpmeas.COLTYPE_INTEGER),
                    (self.objects_name.value,
                     cpmi.FF_PARENT%self.primary_objects.value,
                     cpmeas.COLTYPE_INTEGER)]
        if self.method != M_DISTANCE_N:
            columns += cpmi.get_threshold_measurement_columns(self.objects_name.value)
        if self.wants_discard_edge and self.wants_discard_primary:
            columns += cpmi.get_object_measurement_columns(self.new_primary_objects_name.value)
            columns += [(self.new_primary_objects_name.value,
                         cpmi.FF_CHILDREN_COUNT%self.objects_name.value,
                         cpmeas.COLTYPE_INTEGER),
                        (self.objects_name.value,
                         cpmi.FF_PARENT%self.new_primary_objects_name.value,
                         cpmeas.COLTYPE_INTEGER)]
            columns += [(self.primary_objects.value,
                         cpmi.FF_CHILDREN_COUNT%self.new_primary_objects_name.value,
                         cpmeas.COLTYPE_INTEGER),
                        (self.new_primary_objects_name.value,
                         cpmi.FF_PARENT%self.primary_objects.value,
                         cpmeas.COLTYPE_INTEGER)]

        return columns

def get_measurement_columns(self, pipeline):
        '''Return column definitions for measurements made by this module'''
        
        object_name = self.object_name.value
        remaining_object_name = self.remaining_objects.value
        columns = I.get_object_measurement_columns(self.remaining_objects.value)
        columns += [(object_name, I.FF_CHILDREN_COUNT % remaining_object_name,
                     cpmeas.COLTYPE_INTEGER),
                    (remaining_object_name, I.FF_PARENT % object_name,
                     cpmeas.COLTYPE_INTEGER)]
        return columns