> url = URL.from_text(u'http://localhost/a/b?x=y')
            >>> child_url = url.child(u"c", u"d")
            >>> child_url.to_text()
            u'http://localhost/a/b/c/d?x=y'

        Args:
           segments (unicode): Additional parts to be joined and added to
              the path, like :func:`os.path.join`. Special characters
              in segments will be percent encoded.

        Returns:
           URL: A copy of the current URL with the extra path segments.

        c