Delete cookie.

        Creates new empty expired cookie.

def del_cookie(self, name: str, *,
                   domain: Optional[str]=None,
                   path: str='/') -> None:
        """Delete cookie.

        Creates new empty expired cookie.
        """
        # TODO: do we need domain/path here?
        self._cookies.pop(name, None)
        self.set_cookie(name, '', max_age=0,
                        expires="Thu, 01 Jan 1970 00:00:00 GMT",
                        domain=domain, path=path)