// This file ONLY is placed into the Public Domain, for any use,
// without warranty, 2018 by Wilson Snyder

module top
  (input d,
   output ext0,
   output ext1,
   output extx,
   output extz);

   assign ext0 = (d === 1'b0);
   assign ext1 = (d === 1'b1);
   assign extx = (d === 1'bx);
   assign extz = (d === 1'bz);
endmodule