code: function createTemplateValue(start, end) {
      var value = "";
      while (start <= end) {
        if (tokens[start].value) {
          value += tokens[start].value;
        } else if (tokens[start].type !== tt.template) {
          value += tokens[start].type.label;
        }
        start++;
      }
      return value;
    }
docs: append the values between start and end