code: private static boolean isParamLiteral(String param) {
      try {
        Double.parseDouble(param);
        return true;
      } catch (NumberFormatException e) {
        // Check to see if the parameter is a literal - either a quoted string or
        // numeric literal
        if (param.length() > 1
            && (param.charAt(0) == '"' || param.charAt(0) == '\'')
            && param.charAt(0) == param.charAt(param.length() - 1)) {
          return true;
        }
      }
      return false;
    }
docs: Determine if the method parameter a quoted string or numeric literal recognized by Polymer.