code: public static PathImpl lookup(String url)
    {
      PathImpl pwd = getPwd();
  
      if (! url.startsWith("/")) {
        return pwd.lookup(url, null);
      }
      else {
        return PWD.lookup(url, null);
      }
    }
docs: Returns a new path relative to the current directory.
  
  @param url a relative or absolute url
  @return the new path.