code: public static Object sum(Iterator<Object> self) {
          return sum(toList(self), null, true);
      }
docs: Sums the items from an Iterator.  This is equivalent to invoking the
  "plus" method on all items from the Iterator. The iterator will become
  exhausted of elements after determining the sum value.
  
  @param self an Iterator for the values to add together
  @return The sum of all of the items
  @since 1.5.5