many new lemmas about take & drop, incl the famous take-lemma Ran expandshort
many new lemmas about take & drop, incl the famous take-lemma
Ran expandshort

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