code: func (c *Client) AppTransferCreate(app string, recipient string) (*AppTransfer, error) {
  	params := struct {
  		App       string `json:"app"`
  		Recipient string `json:"recipient"`
  	}{
  		App:       app,
  		Recipient: recipient,
  	}
  	var appTransferRes AppTransfer
  	return &appTransferRes, c.Post(&appTransferRes, "/account/app-transfers", params)
  }
docs: // Create a new app transfer.
  //
  // app is the unique identifier of app or unique name of app. recipient is the
  // unique email address of account or unique identifier of an account.