def METHOD_NAME(self, param, request):
    """
    Validate a single query parameter (request.args in Flask)
    :type param: dict
    :rtype: str
    """
    # Convert to dict of lists
    query_params = {
        k: request.query_params.getlist(k) for k in request.query_params
    }
    query_params = self.uri_parser.resolve_query(query_params)
    val = query_params.get(param["name"])
    return self.validate_parameter("query", val, param)