[STATEMENT]
lemma "x \<in> undefinedSet"
[PROOF STATE]
proof (prove)
goal (1 subgoal):
 1. x \<in> undefinedSet
[PROOF STEP]
nitpick [expect = genuine]
[PROOF STATE]
proof (prove)
goal (1 subgoal):
 1. x \<in> undefinedSet
[PROOF STEP]
oops