logic in code

Hello ,

I have written below code: I want that if next value in loop(snap_id as id1 variable) is not incremented by 1 like if snap_id=69130 initially and then this is 69132 so I mean if there are some gaps like this then the snap id should be populated otherwise not.I have defined another variable id2 -each time when loop would be iterated this is checking if id1 (new value in loop) is equal to id2(previous value in loop) +1 - if not then print that snap_id but this is not giving desired output .Now,there is no gap in snap id actually