code: func (iter Enumerator) UCount(p Predicate) uint {
  	tally := uint(0)
  	for entry := range iter {
  		if p(entry) {
  			tally++
  		}
  	}
  	return tally
  }
docs: // UCount iterates over a list and keeps a running tally of the number of elements
  // satisfy a predicate.