var wg sync.WaitGroup
	wg.Add(100)
	for i := 0; i < 100; i++ {
		go func() {
			defer wg.Done()
			l.SetFlags(0)
			l.Output(0, "")
		}()
	}
	wg.Wait()
}

func TestFlagAndPrefixSetting(t *testing.T) {
	var b bytes.Buffer
	l := New(&b, "Test:", LstdFlags)
	f := l.Flags()
	if f != LstdFlags {
		t.Errorf("Flags 1: expected %x got %x", LstdFlags, f)
	}
	l.SetFlags(f | Lmicroseconds)