[something 9]
|  [something 8]
|  |  [something 7]
|  |  |  [something 6]
|  |  |  |  [something 5]
|  |  |  |  |  [something 4]
|  |  |  |  |  |  [something 3]
|  |  |  |  |  |  |  [something 2]
|  |  |  |  |  |  |  |  [something 1]
|  |  |  |  |  |  |  |  |  [something 0]
|  |  |  |  |  |  |  |  |  0
|  |  |  |  |  |  |  |  1
|  |  |  |  |  |  |  3
|  |  |  |  |  |  6
|  |  |  |  |  10
|  |  |  |  15
|  |  |  21
|  |  28
|  36
45
Backtrace:
In unknown file:
   ?: 0* (begin (load "./tr.scm") (main (command-line)) (quit))
   ?: 1* [main ("./tr.scm")]
In ./tr.scm:
  30: 2  [something ...
  30: 3*  [string->number ...
  30: 4*   [list-ref ("./tr.scm") 1]

./tr.scm:30:30: In procedure list-ref in expression (list-ref (car args) 1):
./tr.scm:30:30: Argument 2 out of range: 1