code: def delete_async(blob_key, **options):
    
    if not isinstance(blob_key, (basestring, BlobKey)):
      raise TypeError('Expected blob key, got %r' % (blob_key,))
    rpc = blobstore.create_rpc(**options)
    yield blobstore.delete_async(blob_key, rpc=rpc)
docs: Async version of delete().