def list_slack():
    """List channels & users in slack."""
    try:
        token = os.environ['SLACK_TOKEN']
        slack = Slacker(token)

        # Get channel list
        response = slack.channels.list()
        channels = response.body['channels']
        for channel in channels:
            print(channel['id'], channel['name'])
            # if not channel['is_archived']:
            # slack.channels.join(channel['name'])
        print()

        # Get users list
        response = slack.users.list()
        users = response.body['members']
        for user in users:
            if not user['deleted']:
                print(user['id'], user['name'], user['is_admin'], user[
                    'is_owner'])
        print()
    except KeyError as ex:
        print('Environment variable %s not set.' % str(ex))
List channels & users in slack.