UniversalMarkdown.Parse.Elements.ListBlock.AppendTextToListItem C# (CSharp) Method

        private static void AppendTextToListItem(ListItemBlock listItem, string markdown, int start, int end)
        {
            ListItemBuilder listItemBuilder = null;
            if (listItem.Blocks.Count > 0)
                listItemBuilder = listItem.Blocks[listItem.Blocks.Count - 1] as ListItemBuilder;
            if (listItemBuilder == null)
            {
                // Add a new block.
                listItemBuilder = new ListItemBuilder();
                listItem.Blocks.Add(listItemBuilder);
            }
            var builder = listItemBuilder.Builder;
            if (builder.Length >= 2 &&
                Common.IsWhiteSpace(builder[builder.Length - 2]) &&
                Common.IsWhiteSpace(builder[builder.Length - 1]))
            {
                builder.Length -= 2;
                builder.AppendLine();
            }
            else if (builder.Length > 0)
                builder.Append(' ');
            builder.Append(markdown.Substring(start, end - start));
        }