def _check_arima_start(start, k_ar, k_diff, method, dynamic):
    if start < 0:
        raise ValueError("The start index %d of the original series "
                         "has been differenced away" % start)
    elif (dynamic and 'mle' not in method) and start < k_ar:
        raise ValueError("Start must be >= k_ar for conditional MLE "
                         "or dynamic forecast. Got %d" % start)
dataset/ETHPy150Open statsmodels/statsmodels/statsmodels/tsa/arima_model.py/_check_arima_start/operator `or` -> `and`