code: def _base_case(x):
      # if x is empty, return false so the other methods return False
      if (x is None) or (x.shape[0] == 0):
          return False
      return True
  
imports: from sklearn.base import BaseEstimator
  from sklearn.linear_model import LinearRegression
  from statsmodels import api
  from abc import ABCMeta, abstractmethod
  import numpy
  from ..compat.numpy import DTYPE
  from ..decorators import deprecated
  from ..utils.array import c, diff, check_endog
  from .approx import approx
  from ._arima import C_tseries_pp_sum
label_desc: Use image node_id 1 for calling the _BaseStationarityTest obj's underlying member method code with example usage: obj._base_case(x) and returns: True, False