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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 get_client(config_file=None, apikey=None, username=None, userpass=None, service_url=None, verify_ssl_certs=None, select_first=None):
 """Configure the API service and creates a new instance of client. :param str config_file: absolute path to configuration file :param str apikey: apikey from thetvdb :param str username: username used on thetvdb :param str userpass: password used on thetvdb :param str service_url: the url for thetvdb api service :param str verify_ssl_certs: flag for validating ssl certs for service url (https) :param str select_first: flag for selecting first series from search results :returns: tvdbapi client :rtype: tvdbapi_client.api.TVDBClient """

    from oslo_config import cfg

    from tvdbapi_client import api

    if config_file is not None:
        cfg.CONF([], default_config_files=[config_file])
    else:
        if apikey is not None:
            cfg.CONF.set_override('apikey', apikey, 'tvdb')
        if username is not None:
            cfg.CONF.set_override('username', username, 'tvdb')
        if userpass is not None:
            cfg.CONF.set_override('userpass', userpass, 'tvdb')
        if service_url is not None:
            cfg.CONF.set_override('service_url', service_url, 'tvdb')
        if verify_ssl_certs is not None:
            cfg.CONF.set_override('verify_ssl_certs', verify_ssl_certs, 'tvdb')
        if select_first is not None:
            cfg.CONF.set_override('select_first', select_first, 'tvdb')

    return api.TVDBClient()