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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def absent(name):
    '''
    Ensures that the named bridge does not exist, eventually deletes it.

    Args:
        name: The name of the bridge.

    '''

    ret = {'name': name, 'changes': {}, 'result': False, 'comment': ''}

    # Comment and change messages
    comment_bridge_deleted = 'Bridge {0} deleted.'.format(name)
    comment_bridge_notdeleted = 'Unable to delete bridge: {0}.'.format(name)
    comment_bridge_notexists = 'Bridge {0} does not exist.'.format(name)
    changes_bridge_deleted = {name: {'old': 'Bridge {0} exists.'.format(name),
                                     'new': 'Bridge {0} deleted.'.format(name),
                                     }
                              }

    bridge_exists = __salt__['openvswitch.bridge_exists'](name)

    # Dry run, test=true mode
    if __opts__['test']:
        if not bridge_exists:
            ret['result'] = True
            ret['comment'] = comment_bridge_notexists
        else:
            ret['result'] = None
            ret['comment'] = comment_bridge_deleted

        return ret

    if not bridge_exists:
        ret['result'] = True
        ret['comment'] = comment_bridge_notexists
    else:
        bridge_delete = __salt__['openvswitch.bridge_delete'](name)
        if bridge_delete:
            ret['result'] = True
            ret['comment'] = comment_bridge_deleted
            ret['changes'] = changes_bridge_deleted
        else:
            ret['result'] = False
            ret['comment'] = comment_bridge_notdeleted

    return ret