code: def norm_corr(x, y, mode="valid"):
      """Returns the correlation between two ndarrays, by calling np.correlate in
      'same' mode and normalizing the result by the std of the arrays and by
      their lengths. This results in a correlation = 1 for an auto-correlation
      """
  
      return np.correlate(x, y, mode) / (
          np.std(x) * np.std(y) * (x.shape[-1])
      )
  
imports: import numpy
  from numpy.testing import assert_array_almost_equal
  import matplotlib.pyplot
  from statsmodels import regression
  from statsmodels.tsa.arima_process import arma_generate_sample, arma_impulse_response
  from statsmodels.tsa.arima_process import arma_acovf, arma_acf
  from statsmodels.tsa.arima.model import ARIMA
  from statsmodels.tsa.stattools import acf, acovf
  from statsmodels.graphics.tsaplots import plot_acf
label_desc: Use image node_id 12 for calling a global function with example usage: norm_corr(x, y, mode) and returns: unknown