code: function getArrow(originalPath, newPath, originalTarget, newTarget) {
      const arrow = ['>'];
      const isNewTarget = originalTarget !== newTarget; // router
      const isNewPath = originalPath !== newPath; // pathRewrite
      if (isNewPath && !isNewTarget) {
          arrow.unshift('~');
      }
      else if (!isNewPath && isNewTarget) {
          arrow.unshift('=');
      }
      else if (isNewPath && isNewTarget) {
          arrow.unshift('≈');
      }
      else {
          arrow.unshift('-');
      }
      return arrow.join('');
  }
docs: -> normal proxy
  => router
  ~> pathRewrite
  ≈> router + pathRewrite
  
  @param  {String} originalPath
  @param  {String} newPath
  @param  {String} originalTarget
  @param  {String} newTarget
  @return {String}