question about get_cmd_object

[Alexander Belchenko]

C:\work\Bazaar\bzr-repo\bzr>python -c "import bzrlib.commands; print 
bzrlib.commands.get_cmd_object('branch',False)"
Traceback (most recent call last):
   File "<string>", line 1, in <module>
   File "bzrlib\commands.py", line 212, in get_cmd_object
     raise errors.BzrCommandError('unknown command "%s"' % cmd_name)
bzrlib.errors.BzrCommandError: unknown command "branch"


Why I've got error? What is the right way to use this function?