#> ./test-subroutine.pl
Passing in $a: 1, $b: 1, $c: 1: expect p 1 1
  < p >  < 1 > < 1 > 
Passing in $a: 2, $b: 2, $c: 2: expect pp 2 2
  < pp >  < 2 > < 2 > 
Passing in $a: 3, $b: 3, $c: 3: expect 3 w 3
  < 3 >  < w > < 3 > 
#>