recovered metis proof after 115965966e15 (Odd clash of type variables!?);
recovered metis proof after 115965966e15 (Odd clash of type variables!?);

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