_twKBoard( n )
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     Stuff the keyboard with a key code. _twKBoard() supports key codes
     not included in INKEY.CH. The code numbers may be found in the
     'Key Codes' section of this file under 'Reference'. You may
     replace your INKEY.CH with TWINKEY.CH which includes a listing of
     all the codes.

     _twKBoard() can stuff ONLY ONE key at a time.

       Arguments:

     n - 'N' Key code number to stuff.

       Return:

     None.

       Example:

     _twKBoard( K_F1 )