public static MethodInfo Sum_Int64_TSource_2(Type TSource) =>
(s_Sum_Int64_TSource_2 ??
(s_Sum_Int64_TSource_2 = new Func<IQueryable<object>, Expression<Func<object, long>>, long>(Queryable.Sum).GetMethodInfo().GetGenericMethodDefinition()))
.MakeGenericMethod(TSource);