object
  method constraint_ : Type.constraint_ -> Type.constraint_
  method decl : Type.decl -> Type.decl
  method expr : Type.expr -> Type.expr
  method field : Type.field -> Type.field
  method gsummand : Type.gsummand -> Type.gsummand
  method poly_expr : Type.poly_expr -> Type.poly_expr
  method repr : Type.repr -> Type.repr
  method rhs : Type.rhs -> Type.rhs
  method summand : Type.summand -> Type.summand
  method tagspec : Type.tagspec -> Type.tagspec
  method variant : Type.variant -> Type.variant
end