code: func (f *SourceFile) ExecuteTemplate(name, source string, funcMap template.FuncMap, data interface{}) error {
  	tmpl, err := template.New(name).Funcs(DefaultFuncMap).Funcs(funcMap).Parse(source)
  	if err != nil {
  		panic(err) // bug
  	}
  	return tmpl.Execute(f, data)
  }
docs: // ExecuteTemplate executes the template and writes the output to the file.