def header(self, name, value):
        """
        Defines a URL path to match.

        Only call this method if the URL has no path already defined.

        Arguments:
            path (str): URL path value to match. E.g: ``/api/users``.

        Returns:
            self: current Mock instance.
        """
        headers = {name: value}
        self._request.headers = headers
        self.add_matcher(matcher('HeadersMatcher', headers))
Defines a URL path to match.

        Only call this method if the URL has no path already defined.

        Arguments:
            path (str): URL path value to match. E.g: ``/api/users``.

        Returns:
            self: current Mock instance.