careful when calling 'Thm.proof_body_of' -- it can throw exceptions
careful when calling 'Thm.proof_body_of' -- it can throw exceptions

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