IF YOU CAN SEE THIS go to http://www.cs.cornell.edu/Info/People/sfa/Nuprl/Shared/Xindentation_hack_doc.html
At:
ma-join-list-is-empty L:MsgA List. ma-is-empty((L)) ~ reduce(M,x. ma-is-empty(M)x;true;L)
By:
InductionOnList THEN Unfold `ma-join-list` 0 THEN Reduce 0
THEN
Try (Fold `ma-join-list` 0)