code: func NewPublicKeysFromFile(user, pemFile, password string) (*PublicKeys, error) {
  	bytes, err := ioutil.ReadFile(pemFile)
  	if err != nil {
  		return nil, err
  	}
  
  	return NewPublicKeys(user, bytes, password)
  }
docs: // NewPublicKeysFromFile returns a PublicKeys from a file containing a PEM
  // encoded private key. An encryption password should be given if the pemBytes
  // contains a password encrypted PEM block otherwise password should be empty.