string ConvertToString(Project project, ExpressionOptions options)
        {
            StringBuilder sb = new StringBuilder();

            foreach (object o in objects)
            {
                string s = o as string;
                if (s != null)
                {
                    sb.Append(s);
                    continue;
                }

                IReference br = o as IReference;
                if (br != null)
                {
                    sb.Append(br.ConvertToString(project, options));
                }
                else
                {
                    throw new Exception("BUG: Invalid type in objects collection.");
                }
            }
            return(sb.ToString());
        }