// isStandaloneFile reports whether a file with the given contents should be // considered a 'standalone main file', meaning a package that consists of only // a single file. func isStandaloneFile(src []byte, standaloneTags []string) bool { … } // walkConstraints calls f for each constraint expression in the file, until // all constraints are exhausted or f returns false. func walkConstraints(file *ast.File, f func(constraint.Expr) bool) { … }