If clause and another choice, if choice is not made in x seconds [duplicate]

This question already has an answer here:

• Keyboard input with timeout? 14 answers

Is it possible to make an if clause, that fires after x seconds if user did not enter an input?; Someone has a choice between 2 options. If he enters one of them it fires. If he does not enter option within 30 seconds, another choice (none of the 2 options) fires.