Check if the given name is the pk field, suffixed or not with "__eq"

def _field_is_pk(self, field_name):
        """Check if the given name is the pk field, suffixed or not with "__eq" """
        if self.cls._field_is_pk(field_name):
            return True
        if field_name.endswith('__eq') and self.cls._field_is_pk(field_name[:-4]):
            return True
        return False