convert lemma fix_cprod to use Pair, fst, snd
convert lemma fix_cprod to use Pair, fst, snd

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle