$ perl -d pm_1202351.pl

Loading DB routines from perl5db.pl version 1.49_001
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(pm_1202351.pl:4):        my %son_father;
  DB<1> c 41

         SON_FATHER Hash Operations

a- Add a son-father pair
d- Delete a son-father pair
e- exit the program
g- Get a father
o- Output the hash neatly
r- Replace a father
x- get a grand father


Make your choice: g
main::(pm_1202351.pl:41):         if ($choice eq 'a'){
  DB<2> p $choice
g
  DB<3> n
main::(pm_1202351.pl:54):         if ($choice eq 'd') {