code: func (p *Project) FunctionDirNames() (list []string, err error) {
  	dir := filepath.Join(p.Path, functionsDir)
  
  	files, err := ioutil.ReadDir(dir)
  	if err != nil {
  		return nil, err
  	}
  
  	for _, file := range files {
  		if file.IsDir() {
  			list = append(list, file.Name())
  		}
  	}
  
  	return list, nil
  }
docs: // FunctionDirNames returns a list of function directory names.