SimpleAsyncResult.isValid

Ensures that the data passed to the _finish function of an async operation is consistent. Three checks are performed.

First, result is checked to ensure that it is really a #GSimpleAsyncResult. Second, source is checked to ensure that it matches the source object of result. Third, source_tag is checked to ensure that it is equal to the source_tag argument given to [gio.simple_async_result.SimpleAsyncResult.new_] (which, by convention, is a pointer to the _async function corresponding to the _finish function from which this function is called). (Alternatively, if either source_tag or result's source tag is null, then the source tag check is skipped.)