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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(client=None):
 """ Get an ElasticAPM client. :param client: :return: :rtype: elasticapm.base.Client """

    global _client

    tmp_client = client is not None
    if not tmp_client:
        config = getattr(django_settings, "ELASTIC_APM", {})
        client = config.get("CLIENT", default_client_class)

    if _client[0] != client:
        client_class = import_string(client)
        instance = client_class()
        if not tmp_client:
            _client = (client, instance)
        return instance
    return _client[1]