def lookup_foreign_key_field(self, options, field_name):
        '''Make a field lookup converting __ into real models fields'''
        if '__' != field_name:
            fk_name, field_name = field_name.split('__', 1)
            fields = [f for f in options.fields if f.name == fk_name]
            if len(fields) > 0:
                field_class = fields[0]
            else:
                raise FieldError('No field %s in %s' % (fk_name, options))
            foreign_model_options = field_class.rel.to._meta
            return self.lookup_foreign_key_field(foreign_model_options, field_name)
        else:
            return options.get_field_by_name(field_name)
dataset/ETHPy150Open gerry/django-jqgrid/jqgrid.py/JqGrid.lookup_foreign_key_field/operator `in` -> `!=`