If blocking is false, then stream must be a
#GPollableOutputStream for which
gio.pollable_output_stream.PollableOutputStream.canPoll returns true or else the
behavior is undefined. If blocking is true, then stream does not
need to be a #GPollableOutputStream.
Tries to write to stream, as with gio.output_stream.OutputStream.write (if blocking is true) or gio.pollable_output_stream.PollableOutputStream.writeNonblocking (if blocking is false). This can be used to more easily share code between blocking and non-blocking implementations of a method.
If blocking is false, then stream must be a #GPollableOutputStream for which gio.pollable_output_stream.PollableOutputStream.canPoll returns true or else the behavior is undefined. If blocking is true, then stream does not need to be a #GPollableOutputStream.