WithoutK5.agda:12,24-28
I'm not sure if there should be a case for the constructor refl,
because I get stuck when trying to solve the following unification
problems (inferred index ≟ expected index):
  refl ≟ refl
Possible reasons why unification failed:
  Cannot apply injectivity to the equation refl = refl of type
  _≡_ {A} a a because I cannot generalize over the indices [a].
  Cannot eliminate reflexive equation refl = refl of type _≡_ {A} a a
  because K has been disabled.
when checking that the pattern refl has type
_≡_ {_≡_ {A} a a} refl refl
