This is the function type of the callback used for the #GSource returned by gio.pollable_input_stream.PollableInputStream.createSource and gio.pollable_output_stream.PollableOutputStream.createSource.
it should return false if the source should be removed.
This is the function type of the callback used for the #GSource returned by gio.pollable_input_stream.PollableInputStream.createSource and gio.pollable_output_stream.PollableOutputStream.createSource.