public static UnifiedLinqExpression ToLinqExpression(
     this UnifiedLinqQuery singleton)
 {
     if (singleton == null)
     {
         return(UnifiedLinqExpression.Create());
     }
     return(UnifiedLinqExpression.Create(singleton));
 }
 public static UnifiedLinqExpression ToLinqExpression(
     this IEnumerable <UnifiedLinqQuery> collection)
 {
     return(UnifiedLinqExpression.Create(collection));
 }