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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 _limit_is_valid_or_none(self, params):
 """ Validates that a given limit is not present or is well-formed. :param params: Query params. :return: Returns True if a limit is present or is well-formed. """

        if not "limit" in params or not params["limit"]:
            return True
        if not isinstance(params["limit"], int) or params["limit"] < 1:
            return False
        if not "order_by" in params:
            return False
        return True