Feature Request: Add Nested Groups

Hi - I've been using sshch for a few months now and really enjoy its simplicity. One feature I wish it had is the ability to nest a group inside another group. The use case I have is having multiple sites with different environments. Say I have LocationA, LocationB, and LocationC. I'd like to have three groups nested in each location; Prod, Dev, & Stage. If this is possible could you add this?

1. LocationA
   • Prod
     • Device1
     • Device2
     • Devicex
   • Dev
     • Device1
     • Device2
     • Devicex
   • Stage
     • Device1
     • Device2
     • Devicex
2. Location B
   • Prod
     • Device1
     • Device2
     • Devicex
   • Dev
     • Device1
     • Device2
     • Devicex
   • Stage
     • Device1
     • Device2
     • Devicex
3. Location C
   • Prod
     • Device1
     • Device2
     • Devicex
   • Dev
     • Device1
     • Device2
     • Devicex
   • Stage
     • Device1
     • Device2
     • Devicex

Thank you