code: def get_current_url(environ, root_only=False, strip_querystring=False, host_only=False):
      
      tmp = [environ["wsgi.url_scheme"], "://", get_host(environ)]
      cat = tmp.append
      if host_only:
          return "".join(tmp) + "/"
      cat(quote(environ.get("SCRIPT_NAME", "").rstrip("/")))
      if root_only:
          cat("/")
      else:
          cat(quote("/" + environ.get("PATH_INFO", "").lstrip("/")))
          if not strip_querystring:
              qs = environ.get("QUERY_STRING")
              if qs:
                  cat("?" + qs)
      return "".join(tmp)
docs: A handy helper function that recreates the full URL for the current
      request or parts of it.  Here an example:
  
      >>> from werkzeug import create_environ
      >>> env = create_environ("/?param=foo", "http://localhost/script")
      >>> get_current_url(env)
      'http://localhost/script/?param=foo'
      >>> get_current_url(env, root_only=True)
      'http://localhost/script/'
      >>> get_current_url(env, host_only=True)
      'http://localhost/'
      >>> get_current_url(env, strip_querystring=True)
      'http://localhost/script/'
  
      :param environ: the WSGI environment to get the current URL from.
      :param root_only: set `True` if you only want the root URL.
      :param strip_querystring: set to `True` if you don't want the querystring.
      :param host_only: set to `True` if the host URL should be returned.