code: func addStagedSigner(notaryRepo client.Repository, newSigner data.RoleName, signerKeys []data.PublicKey) error {
  	// create targets/<username>
  	if err := notaryRepo.AddDelegationRoleAndKeys(newSigner, signerKeys); err != nil {
  		return err
  	}
  	if err := notaryRepo.AddDelegationPaths(newSigner, []string{""}); err != nil {
  		return err
  	}
  
  	// create targets/releases
  	if err := notaryRepo.AddDelegationRoleAndKeys(trust.ReleasesRole, signerKeys); err != nil {
  		return err
  	}
  	return notaryRepo.AddDelegationPaths(trust.ReleasesRole, []string{""})
  }
docs: // stages changes to add a signer with the specified name and key(s).  Adds to targets/<name> and targets/releases