How to understand nimprof report?

[alexeypetrushin]

I'm trying to find the bottleneck in my code - the function that consumes most 
of the time. But I don't understand how to interpret the `nimprof` report as it 
seems like it has duplicate entries.

In its default settings `nimprof` report included std and system functions, I 
altered it a little bit, excluding Nim std and system functions (I filter out 
the stack trace, excluding system functions).

It kinda works, but produces strange results containing the duplicates, I was 
using code example from [Nim in Action, Profiling your 
code](https://nim-lang.org/blog/2017/10/02/documenting-profiling-and-debugging-nim-code.html#profiling-your-code)

The code [playground](https://repl.it/@alexeypetrushin/profiling#main.nim):
    
    
    import strutils, custom_nimprof
    
    proc ab() =
      echo("Found letter")
    
    proc num() =
      echo("Found number")
    
    proc diff() =
      echo("Found something else")
    
    proc analyse(x: string) =
      var i = 0
      while i < x.len:
        case x[i]
        of Letters: ab()
        of {'0' .. '9'}: num()
        else: diff()
        i.inc
    
    for i in 0 .. 10000:
      analyse("uyguhijkmnbdv44354gasuygiuiolknchyqudsayd12635uha")
    
    
    Run

It produces the following result (with excluded nim core functions):
    
    
    writing profile_results.txt...
    total executions of each stack trace:
    Entry: 1/5 Calls: 67/125 = 53.60% [sum: 67; 67/125 = 53.60%]
      /main.nim: analyse 125/125 = 100.00%
      /main.nim: main 125/125 = 100.00%
    Entry: 2/5 Calls: 38/125 = 30.40% [sum: 105; 105/125 = 84.00%]
      /main.nim: ab 50/125 = 40.00%
      /main.nim: analyse 125/125 = 100.00%
      /main.nim: main 125/125 = 100.00%
    Entry: 3/5 Calls: 12/125 = 9.60% [sum: 117; 117/125 = 93.60%]
      /main.nim: ab 50/125 = 40.00%
      /main.nim: analyse 125/125 = 100.00%
      /main.nim: main 125/125 = 100.00%
    Entry: 4/5 Calls: 5/125 = 4.00% [sum: 122; 122/125 = 97.60%]
      /main.nim: num 8/125 = 6.40%
      /main.nim: analyse 125/125 = 100.00%
      /main.nim: main 125/125 = 100.00%
    Entry: 5/5 Calls: 3/125 = 2.40% [sum: 125; 125/125 = 100.00%]
      /main.nim: num 8/125 = 6.40%
      /main.nim: analyse 125/125 = 100.00%
      /main.nim: main 125/125 = 100.00%
    
    
    Run

You may notice that the call stack in entries 2/5 and 3/5 is the same. Why?

Aren't they supposed to be grouped together?