c_g_pollable_output_stream_write_nonblocking

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
ptrdiff_t function(GPollableOutputStream* stream, void* buffer, size_t count, GCancellable* cancellable, GError** err) c_g_pollable_output_stream_write_nonblocking;

Meta