Goal:
    A : Type  B : Type  C : Type  R : A → B → C → Type
  ============================
   (All3_nil = All3_nil)


DEBUG:Going to execute:
<coq-core.plugins.ltac::constructor@0>

Goals:

DEBUG:Going to execute:
constructor

Goals:

DEBUG:Going to execute:
<coq-core.plugins.ltac::constructor@0>