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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 sanitize_http_request_querystring(client, event):
 """ Sanitizes http request query string :param client: an ElasticAPM client :param event: a transaction or error event :return: The modified event """

    try:
        query_string = force_text(event["context"]["request"]["url"]["search"], errors="replace")
    except (KeyError, TypeError):
        return event
    if "=" in query_string:
        sanitized_query_string = _sanitize_string(query_string, "&", "=")
        full_url = event["context"]["request"]["url"]["full"]
        event["context"]["request"]["url"]["search"] = sanitized_query_string
        event["context"]["request"]["url"]["full"] = full_url.replace(query_string, sanitized_query_string)
    return event