orderbook subcommand is broken

[sneak]

sneak@rabotnik:~$ steempy orderbook -h
usage: steempy orderbook [-h] [--chart]

optional arguments:
  -h, --help  show this help message and exit
  --chart     Enable charting (requires matplotlib)
sneak@rabotnik:~$ steempy orderbook 
No valid command given
sneak@rabotnik:~$ steempy orderbook --chart
No valid command given
sneak@rabotnik:~$