bug1.lean:9:7: error: type mismatch at definition 'and_intro1', has type
  ∀ p q,
    p → q → (∀ c, (p → q → c) → c)
but is expected to have type
  ∀ p q,
    p → q → a
bug1.lean:13:7: error: type mismatch at definition 'and_intro2', has type
  ∀ p q,
    p → q → (∀ c, (p → q → c) → c)
but is expected to have type
  ∀ p q,
    p → q → p ∧ p
bug1.lean:17:7: error: type mismatch at definition 'and_intro3', has type
  ∀ p q,
    p → q → (∀ c, (p → q → c) → c)
but is expected to have type
  ∀ p q,
    p → q → q ∧ p
and_intro4 : ∀ p q, p → q → p ∧ q