wrap_key_async
Description:
public async uint8[] wrap_key_async (Object wrapper, Mechanism mechanism, Object wrapped, Cancellable? cancellable) throws Error
  
  Wrap a key into a byte stream.
This call will return immediately and complete asynchronously.
Parameters:
| this | The session to use. | 
| wrapper | The key to use for wrapping. | 
| mechanism | The mechanism to use for wrapping. | 
| wrapped | The key to wrap. | 
| cancellable | Optional cancellation object or  | 
| callback | Called when the operation completes. | 
| user_data | Data to pass to the callback. |