Flags for commands are also executing for the main parser

[raveesh-me]

➜  flutput git:(master) ✗ dart lib/flutput.dart -h      
lib/flutput.dart: Warning: Interpreting this as package URI, 'package:flutput/flutput.dart'.
-h, --help    Displays help for any given command
➜  flutput git:(master) ✗ dart lib/flutput.dart fast -h
lib/flutput.dart: Warning: Interpreting this as package URI, 'package:flutput/flutput.dart'.
-h, --help    shows help for fast command
-h, --help    Displays help for any given command

when I run flutput fast -h, I would not want the result of flutput -h I am using callbacks when adding flags. Possible workarounds?