IronRuby.Builtins.RangeOps.StepString C# (CSharp) Method

        private static object StepString(EachStorage/*!*/ storage, BlockParam/*!*/ block, Range/*!*/ self, MutableString begin, MutableString end, int step) {
            Assert.NotNull(storage, block, self);
            CheckStep(step);
            object result;
            MutableString item = begin;
            int comp;

            while ((comp = Protocols.Compare(storage, item, end)) < 0) {
                if (block.Yield(item.Clone(), out result)) {
                    return result;
                }

                if (ReferenceEquals(item, begin)) {
                    item = item.Clone();
                }

                // TODO: this can be optimized 
                for (int i = 0; i < step; i++) {
                    MutableStringOps.SuccInPlace(item);
                }

                if (item.Length > end.Length) {
                    return self;
                }
            }

            if (comp == 0 && !self.ExcludeEnd) {
                if (block.Yield(item.Clone(), out result)) {
                    return result;
                }
            }
            return self;
        }