auxDeclIssue.lean:5:3: error: tactic 'assumption' failed, 
case main
ex1 : False
⊢ False
auxDeclIssue.lean:11:2: error: tactic 'subst' failed, did not find equation for eliminating 'x'
case main
x y : Nat
ex2 : x=y
⊢ x=y