IOStream.spliceAsync

void spliceAsync(gio.iostream.IOStream stream2,  gio.types.IOStreamSpliceFlags flags,  int  ioPriority,  gio.cancellable.Cancellable cancellable =  null,  gio.types.AsyncReadyCallback callback =  null)

Asynchronously splice the output stream of stream1 to the input stream of stream2, and splice the output stream of stream2 to the input stream of stream1.

When the operation is finished callback will be called. You can then call [gio.iostream.IOStream.spliceFinish] to get the result of the operation.

Parameters

`stream2`	a #GIOStream.
`flags`	a set of #GIOStreamSpliceFlags.
`ioPriority`	the io priority of the request.
`cancellable`	optional #GCancellable object, null to ignore.
`callback`	a #GAsyncReadyCallback to call when the request is satisfied