// copy function will only return non-nil for AST values that
	// need to change.
	// Copy itself returns either a copy or nil.
	Copy(copy func(AST) AST, skip func(AST) bool) AST

	// Implement the fmt.GoStringer interface.
	GoString() string
	goString(indent int, field string) string
}

// ASTToString returns the demangled name of the AST.
func ASTToString(a AST, options ...Option) string {
	tparams := true