section
  variable A : Type
  inductive list : Type :=
  nil  : list,
  cons : A → list → list
end

check list.{1}
check list.cons.{1}

section
  variable A : Type
  inductive tree : Type :=
  node : A → forest → tree
  with forest : Type :=
  fnil  : forest,
  fcons : tree → forest → forest
  check tree
  check forest
end

check tree.{1}
check forest.{1}