Tuned function extend_lexicon.
(*  Title:      CTT/ex/ROOT.ML
    ID:         $Id$
    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
    Copyright   1991  University of Cambridge
Executes all examples for Constructive Type Theory. 
*)
print_depth 2;  
time_use "typechk.ML";
time_use "elim.ML";
time_use "equal.ML";
time_use "synth.ML";