code: func (t *Pot) each(f func(Val) bool) bool {
  	if t == nil || t.size == 0 {
  		return false
  	}
  	for _, n := range t.bins {
  		if !n.each(f) {
  			return false
  		}
  	}
  	return f(t.pin)
  }
docs: // each is a synchronous iterator over the elements of pot with function f.
  // the iteration ends if the function return false or there are no more elements.