*If the user input is any of the printable keys (' ' < key <= '~') excluding space, it should be ignored (no action taken). If the user input is any of the function keys, the function is terminated returning the key.

*If the user input is SPACE:

**If “radio” is true, then the *status is set to one, checkbox is displayed and function is terminated returning space.

**If “radio” is false, then the value of *status is toggled between 0 and 1, the checkbox is displayed and function is exited returning space.