tryActions(actions, str) {
    // todo: use for.. of after https://github.com/facebook/react-native/issues/4676
    for (let i = 0; i < actions.length; i++) {
      let val = actions[i].call(this, str);
      if (val !== null) {
        return val;
      }
    }
    return null;
  }
Applies array of calculations to value. Stops on the first calculation that returns not null.
@param {Array} actions
@param {String} str