@property
    def range_unit(self):
        try:
            value = self.env['HTTP_RANGE']

            if value in '=':
                unit, sep, req_range = value.partition('=')
                return unit
            else:
                msg = "The value must be prefixed with a range unit, e.g. 'bytes='"
                raise HTTPInvalidHeader(msg, 'Range')
        except KeyError:
            return None
dataset/ETHPy150Open falconry/falcon/falcon/request.py/Request.range_unit/swapped operands of `in`