How to use the patroni.ctl.PatroniCtlException function in patroni

if candidate and candidate not in candidate_names:
        raise PatroniCtlException('Member {0} does not exist in cluster {1}'.format(candidate, cluster_name))

    scheduled_at_str = None
    scheduled_at = None

    if action == 'switchover':
        if scheduled is None and not force:
            next_hour = (datetime.datetime.now() + datetime.timedelta(hours=1)).strftime('%Y-%m-%dT%H:%M')
            scheduled = click.prompt('When should the switchover take place (e.g. ' + next_hour + ' ) ',
                                     type=str, default='now')

        scheduled_at = parse_scheduled(scheduled)
        if scheduled_at:
            if cluster.is_paused():
                raise PatroniCtlException("Can't schedule switchover in the paused state")
            scheduled_at_str = scheduled_at.isoformat()

    failover_value = {'leader': master, 'candidate': candidate, 'scheduled_at': scheduled_at_str}

    logging.debug(failover_value)

    # By now we have established that the leader exists and the candidate exists
    click.echo('Current cluster topology')
    output_members(dcs.get_cluster(), cluster_name)

    if not force:
        demote_msg = ', demoting current master ' + master if master else ''
        if scheduled_at_str:
            if not click.confirm('Are you sure you want to schedule {0} of cluster {1} at {2}{3}?'
                                 .format(action, cluster_name, scheduled_at_str, demote_msg)):
                raise PatroniCtlException('Aborting scheduled ' + action)

dcs = get_dcs(obj, cluster_name)
    cluster = dcs.get_cluster()
    if cluster and cluster.initialize is not None:
        raise PatroniCtlException("This cluster is already initialized")

    if not dcs.initialize(create_new=True, sysid=sysid):
        # initialize key already exists, don't touch this cluster
        raise PatroniCtlException("Initialize key for cluster {0} already exists".format(cluster_name))

    set_defaults(obj, cluster_name)

    # make sure the leader keys will never expire
    if not (touch_member(obj, dcs) and dcs.attempt_to_acquire_leader(permanent=True)):
        # we did initialize this cluster, but failed to write the leader or member keys, wipe it down completely.
        dcs.delete_cluster()
        raise PatroniCtlException("Unable to install permanent leader for cluster {0}".format(cluster_name))
    click.echo("Cluster {0} has been created successfully".format(cluster_name))

def get_members(cluster, cluster_name, member_names, role, force, action, ask_confirmation=True):
    candidates = {m.name: m for m in cluster.members}

    if not force or role:
        if not member_names and not candidates:
            raise PatroniCtlException('{0} cluster doesn\'t have any members'.format(cluster_name))
        output_members(cluster, cluster_name)

    if role:
        role_names = [m.name for m in get_all_members(cluster, role)]
        if member_names:
            member_names = list(set(member_names) & set(role_names))
            if not member_names:
                raise PatroniCtlException('No {0} among provided members'.format(role))
        else:
            member_names = role_names

    if not member_names and not force:
        member_names = [click.prompt('Which member do you want to {0} [{1}]?'.format(action,
                        ', '.join(candidates.keys())), type=str, default='')]

    for member_name in member_names:
        if member_name not in candidates:
            raise PatroniCtlException('{0} is not a member of cluster'.format(member_name))

    members = [candidates[n] for n in member_names]
    if ask_confirmation:
        confirm_members_action(members, force, action)
    return members

if master is not None and cluster.leader and cluster.leader.member.name != master:
        raise PatroniCtlException('Member {0} is not the leader of cluster {1}'.format(master, cluster_name))

    # excluding members with nofailover tag
    candidate_names = [str(m.name) for m in cluster.members if m.name != master and not m.nofailover]
    # We sort the names for consistent output to the client
    candidate_names.sort()

    if not candidate_names:
        raise PatroniCtlException('No candidates found to {0} to'.format(action))

    if candidate is None and not force:
        candidate = click.prompt('Candidate ' + str(candidate_names), type=str, default='')

    if action == 'failover' and not candidate:
        raise PatroniCtlException('Failover could be performed only to a specific candidate')

    if candidate == master:
        raise PatroniCtlException(action.title() + ' target and source are the same.')

    if candidate and candidate not in candidate_names:
        raise PatroniCtlException('Member {0} does not exist in cluster {1}'.format(candidate, cluster_name))

    scheduled_at_str = None
    scheduled_at = None

    if action == 'switchover':
        if scheduled is None and not force:
            next_hour = (datetime.datetime.now() + datetime.timedelta(hours=1)).strftime('%Y-%m-%dT%H:%M')
            scheduled = click.prompt('When should the switchover take place (e.g. ' + next_hour + ' ) ',
                                     type=str, default='now')

p_file,
    password,
    username,
    dbname,
    fmt='tsv',
):
    if role is not None and member is not None:
        raise PatroniCtlException('--role and --member are mutually exclusive options')
    if member is None and role is None:
        role = 'master'

    if p_file is not None and command is not None:
        raise PatroniCtlException('--file and --command are mutually exclusive options')

    if p_file is None and command is None:
        raise PatroniCtlException('You need to specify either --command or --file')

    connect_parameters = {}
    if username:
        connect_parameters['username'] = username
    if password:
        connect_parameters['password'] = click.prompt('Password', hide_input=True, type=str)
    if dbname:
        connect_parameters['database'] = dbname

    if p_file is not None:
        command = p_file.read()

    dcs = get_dcs(obj, cluster_name)

    cursor = None
    for _ in watching(w, watch, clear=False):

def toggle_pause(config, cluster_name, paused, wait):
    dcs = get_dcs(config, cluster_name)
    cluster = dcs.get_cluster()
    if cluster.is_paused() == paused:
        raise PatroniCtlException('Cluster is {0} paused'.format(paused and 'already' or 'not'))

    members = []
    if cluster.leader:
        members.append(cluster.leader.member)
    members.extend([m for m in cluster.members if m.api_url and (not members or members[0].name != m.name)])

    for member in members:
        try:
            r = request_patroni(member, 'patch', 'config', {'pause': paused or None})
        except Exception as err:
            logging.warning(str(err))
            logging.warning('Member %s is not accessible', member.name)
            continue

        if r.status == 200:
            if wait:

scheduled_at_str = scheduled_at.isoformat()

    failover_value = {'leader': master, 'candidate': candidate, 'scheduled_at': scheduled_at_str}

    logging.debug(failover_value)

    # By now we have established that the leader exists and the candidate exists
    click.echo('Current cluster topology')
    output_members(dcs.get_cluster(), cluster_name)

    if not force:
        demote_msg = ', demoting current master ' + master if master else ''
        if scheduled_at_str:
            if not click.confirm('Are you sure you want to schedule {0} of cluster {1} at {2}{3}?'
                                 .format(action, cluster_name, scheduled_at_str, demote_msg)):
                raise PatroniCtlException('Aborting scheduled ' + action)
        else:
            if not click.confirm('Are you sure you want to {0} cluster {1}{2}?'
                                 .format(action, cluster_name, demote_msg)):
                raise PatroniCtlException('Aborting ' + action)

    r = None
    try:
        member = cluster.leader.member if cluster.leader else cluster.get_member(candidate, False)

        r = request_patroni(member, 'post', action, failover_value)

        # probably old patroni, which doesn't support switchover yet
        if r.status == 501 and action == 'switchover' and b'Server does not support this operation' in r.data:
            r = request_patroni(member, 'post', 'failover', failover_value)

        if r.status in (200, 202):

def parse_dcs(dcs):
    if dcs is None:
        return None

    parsed = urlparse(dcs)
    scheme = parsed.scheme
    if scheme == '' and parsed.netloc == '':
        parsed = urlparse('//' + dcs)
    port = int(parsed.port) if parsed.port else None

    if scheme == '':
        scheme = ([k for k, v in DCS_DEFAULTS.items() if v['port'] == port] or ['etcd'])[0]
    elif scheme not in DCS_DEFAULTS:
        raise PatroniCtlException('Unknown dcs scheme: {}'.format(scheme))

    default = DCS_DEFAULTS[scheme]
    return yaml.safe_load(default['template'].format(host=parsed.hostname or 'localhost', port=port or default['port']))

def scaffold(obj, cluster_name, sysid):
    dcs = get_dcs(obj, cluster_name)
    cluster = dcs.get_cluster()
    if cluster and cluster.initialize is not None:
        raise PatroniCtlException("This cluster is already initialized")

    if not dcs.initialize(create_new=True, sysid=sysid):
        # initialize key already exists, don't touch this cluster
        raise PatroniCtlException("Initialize key for cluster {0} already exists".format(cluster_name))

    set_defaults(obj, cluster_name)

    # make sure the leader keys will never expire
    if not (touch_member(obj, dcs) and dcs.attempt_to_acquire_leader(permanent=True)):
        # we did initialize this cluster, but failed to write the leader or member keys, wipe it down completely.
        dcs.delete_cluster()
        raise PatroniCtlException("Unable to install permanent leader for cluster {0}".format(cluster_name))
    click.echo("Cluster {0} has been created successfully".format(cluster_name))