public static object Map <TProperty>(this Bag bag, Expression <Func <TProperty, object> > expression)
 {
     return(bag.Map((LambdaExpression)expression));
 }
 public static TValue Map <TValue>(this Bag bag, LambdaExpression expression) where TValue : class
 {
     return(bag.Map(expression) as TValue);
 }
 public static TResult Map <TProperty, TResult>(this Bag bag, Expression <Func <TProperty, object> > expression) where TResult : class
 {
     return(bag.Map((LambdaExpression)expression) as TResult);
 }