human
Write me a the Python program you requested given the following:
Complete the below
def _command(name, description=None):

    ''''Decorate a function used to call a command.
    If you don\'t set *description*, it won\'t be included in help
    (useful for deprecated commands).'
    '''
assistant
#Here is the Python program you requested.
    def decorator(f):
        commands[name] = f
        if description:
            descriptions[name] = description
        return f
    return decorator