added exhausted: ('a, 'b) source -> ('a, 'a list) source;
added exhausted: ('a, 'b) source -> ('a, 'a list) source;

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