}
		x.mode = value
		x.typ = Typ[Int]

	case _Delete:
		// delete(map_, key)
		// map_ must be a map type or a type parameter describing map types.
		// The key cannot be a type parameter for now.
		map_ := x.typ
		var key Type
		if !underIs(map_, func(u Type) bool {
			map_, _ := u.(*Map)
			if map_ == nil {
				check.errorf(x, InvalidDelete, invalidArg+"%s is not a map", x)
				return false
			}

		}
		x.mode = value
		x.typ = Typ[Int]

	case _Delete:
		// delete(map_, key)
		// map_ must be a map type or a type parameter describing map types.
		// The key cannot be a type parameter for now.
		map_ := x.typ
		var key Type
		if !underIs(map_, func(u Type) bool {
			map_, _ := u.(*Map)
			if map_ == nil {
				check.errorf(x, InvalidDelete, invalidArg+"%s is not a map", x)
				return false
			}