<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def command(self, group=None, help="", name=None):
 """Decorator for adding a command to this manager."""

        def decorator(func):
            return self.add_command(func, group=group, help=help, name=name)
        return decorator