Theorem: t'' (Katydid/Std/Tipe.lean)

State before:
⊢ 1 = 2 → False
Tactic:
intro
State after:
a✝ : 1 = 2
⊢ False

State before:
a✝ : 1 = 2
⊢ False
Tactic:
contradiction
State after:
no goals