code: func New() *DefaultLoader {
  	loader := MultiLoader(
  		&TagLoader{},
  		&EnvironmentLoader{},
  		&FlagLoader{},
  	)
  
  	d := &DefaultLoader{}
  	d.Loader = loader
  	d.Validator = MultiValidator(&RequiredValidator{})
  	return d
  }
docs: // New returns a new instance of DefaultLoader without any file loaders.