code: function () {
                      var str, j = i, e;
  
                      if (input.charAt(j) === '~') { j++, e = true } // Escaped strings
                      if (input.charAt(j) !== '`') { return }
  
                      e && $('~');
  
                      if (str = $(/^`([^`]*)`/)) {
                          return new(tree.JavaScript)(str[1], i, e);
                      }
                  }
docs: JavaScript code to be evaluated  `window.location.href`