michael@0: f = eval("\
michael@0:   (function() {\
michael@0:     with({}) {\
michael@0:       yield\
michael@0:     }\
michael@0:     for(let d in[gc()])\
michael@0:     for(b in[0,function(){}]);\
michael@0:   })\
michael@0: ")
michael@0: for (e in f()) {}