Discrepancy in model and implementation

[Abastro]

Just discovered this while trying to conjure Event a -> Event (Event a) up for convenience.

Documentation states the semantics as:

once e = \time0 -> take 1 [(t, a) | (t, a) <- e, time0 <= t]

Note the time0 <= t constraint, which means event occurrence at Moment time is accepted.

However, once is defined using switchE.

once :: MonadMoment m => Event a -> m (Event a)
once e = mdo
  e1 <- switchE e (never <$ e1)
  return e1

Now, from switchE we have

switchE e0 ee0 time0 =
    concat [ trim t1 t2 e | (t1,t2,e) <- intervals ee ]
  where
    laterThan e time0  = [(timex,x) | (timex,x) <- e, time0 < timex ]
    ee                 = [(time0, e0)] ++ (ee0 `laterThan` time0)
    intervals ee       = [(time1, time2, e) | ((time1,e),(time2,_)) <- zip ee (tail ee)]
    trim time1 time2 e = [x | (timex,x) <- e, time1 < timex, timex <= time2]

The trim function only allows event occurrence time1 < timex. Since the intervals ee should start with [(time0, time1, e0), ..], by trim occurrence of e0 before time0 is cut off!

According to this documentation, switchE e (never <$ e1) should not produce any value at the Moment time (time0). Hence, once should drop event occurrence at the Moment time / time0.

I am utterly confused here, which one is right?