Data before pop_sum: 1 2 3
	Total: 0; Data: 1 2 3
	Total: 3; Data: 1 2
	Total: 5; Data: 1
	Total: 6; Data: 
Sum of data: 6
Data after pop_sum: 1 2 3
---
Data before pop_sum_ref: 1 2 3
	Total: 0; Data: 1 2 3
	Total: 3; Data: 1 2
	Total: 5; Data: 1
	Total: 6; Data: 
Sum of data: 6
Data after pop_sum_ref: