Avoid a possible variable name conflict in instantiating a theorem.
Instantiating a theorem variable with new variables created a possible
variable name conflict if a record was defined with a field named
'f', 'x' etc. Using variable indices of 1 avoids the problem.
use "../settings.ML";
use_thy "Tree";
use_thy "Tree2";
use_thy "Plus";
use_thy "case_exprs";
use_thy "fakenat";
use_thy "natsum";
use_thy "pairs";
use_thy "Option2";
use_thy "types";
use_thy "prime_def";
use_thy "simp";
use_thy "Itrev";
use_thy "AdvancedInd";
use_thy "appendix";