def callback(track_transfer_batch, uri, user_param1, ...)

Emitted when the destination URI for a transfer already exists. The handler must call _rb_track_transfer_batch_continue or _rb_track_transfer_batch_cancel when it has figured out what to do.

track_transfer_batch :

instance of RB.TrackTransferBatch that is emitting the signal

uri :

the destination URI that already exists

user_param1 :

first user parameter (if any) specified with the connect() method

... :

additional user parameters (if any)