20. Pressing user keys in a program
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can effectively 'press' a red key on exit from a program, by inserting
the right code into the keyboard buffer. In this example, 128 corresponds to
key <f0>, 129 would be <f1> etc.. The <Break> key is code 138, and note that
this method does not actually cause a Break; this would require the key to be
physically pressed by hand.

 10 *KEY0 LIST|M
 20 *FX138,0,128
 30 PRINT"Here is a Listing..."
 40 END