pred := func(b bool, s string) {
		if b {
			if buf.Len() > 0 {
				buf.WriteString(", ")
			}
			buf.WriteString(s)
		}
	}

	pred(tv.IsVoid(), "void")
	pred(tv.IsType(), "type")
	pred(tv.IsBuiltin(), "builtin")
	pred(tv.IsValue() && tv.Value != nil, "const")
	pred(tv.IsValue() && tv.Value == nil, "value")
	pred(tv.IsNil(), "nil")
	pred(tv.Addressable(), "addressable")

		return r
	}
	return t
}

func (t *Typed) GoString() string {
	return t.goString(0, "")
}

func (t *Typed) goString(indent int, field string) string {
	return fmt.Sprintf("%*s%sTyped:\n%s\n%s", indent, "", field,
		t.Name.goString(indent+2, "Name: "),
		t.Type.goString(indent+2, "Type: "))
}

// Qualified is a name in a scope.
type Qualified struct {
	Scope AST
	Name  AST

		{"(TypeAndValue).Assignable", Method, 5},
		{"(TypeAndValue).HasOk", Method, 5},
		{"(TypeAndValue).IsBuiltin", Method, 5},
		{"(TypeAndValue).IsNil", Method, 5},
		{"(TypeAndValue).IsType", Method, 5},
		{"(TypeAndValue).IsValue", Method, 5},
		{"(TypeAndValue).IsVoid", Method, 5},
		{"Alias", Type, 22},
		{"ArgumentError", Type, 18},
		{"ArgumentError.Err", Field, 18},