Function Reference
— Built-in Function: kbhit ()

Read a single keystroke from the keyboard. If called with one argument, don't wait for a keypress. For example,

          x = kbhit ();

will set x to the next character typed at the keyboard as soon as it is typed.

          x = kbhit (1);

identical to the above example, but don't wait for a keypress, returning the empty string if no key is available.