//
// If Times t and u both contain monotonic clock readings, the operations
// t.After(u), t.Before(u), t.Equal(u), t.Compare(u), and t.Sub(u) are carried out
// using the monotonic clock readings alone, ignoring the wall clock
// readings. If either t or u contains no monotonic clock reading, these
// operations fall back to using the wall clock readings.
//