fn lockStderr(userdata: ?*anyopaque, terminal_mode: ?Io.Terminal.Mode) Io.Cancelable!Io.LockedStderr
fn lockStderr(userdata: ?*anyopaque, terminal_mode: ?Io.Terminal.Mode) Io.Cancelable!Io.LockedStderr { const ev: *Evented = @ptrCast(@alignCast(userdata)); try ev.stderr_mutex.lock(ev); errdefer ev.stderr_mutex.unlock(); return ev.initLockedStderr(terminal_mode); }