Set: pp::colors
  Set: pp::unicode
Error (line: 2, pos: 32) deep recursion was detected at 'REPEAT tactical' (potential solution: increase stack space in your system)
Error (line: 3, pos: 4) invalid 'done' command, proof cannot be produced from this state
Proof state:
a : Bool ⊢ a
Error (line: 4, pos: 0) invalid tactic command, unexpected end of file