mk_const : string * (hol_type * hol_type) list -> term
  # get_const_type "=";;
  val it : hol_type = `:A->A->bool`
  # mk_const("=",[`:num`,`:A`]);;
  val it : term = `(=)`
  # type_of it;;
  val it : hol_type = `:num->num->bool`
  # mk_const("=",[`:num`,`:A`]) = mk_mconst("=",`:num->num->bool`);;
  val it : bool = true