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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 params_to_mongo(query_params):
 """Convert HTTP query params to mongodb query syntax. Converts the parse query params into a mongodb spec. :param dict query_params: return of func:`rest.process_params` """

    if not query_params:
        return {}
    for key, value in query_params.items():
        if isinstance(value, list):
            query_params[key] = {'$in': value}
    return query_params