public PassiveExpression Put(PassiveExpression expression)
        {
            if (expression == null || expression.IsEmpty)
            {
                return(Prout(expression));
            }

            string       handle = expression[0].ToString();
            StreamWriter sw     = OpenFiles[handle] as StreamWriter;

            if (sw == null)
            {
                return(Prout(expression));
            }

            sw.WriteLine("{0}", expression.ToStringBuilder(1));

            PassiveExpression result = PassiveExpression.Build(expression);

            result.Remove(result[0]);
            return(result);
        }