'Returns a copy of self.'

def copy(self, cls=None):

    cls = (cls or BaseResponse)
    assert issubclass(cls, BaseResponse)
    copy = cls()
    copy.status = self.status
    copy._headers = dict(((k, v[:]) for (k, v) in self._headers.items()))
    if self._cookies:
        copy._cookies = SimpleCookie()
        copy._cookies.load(self._cookies.output(header=''))
    return copy
