code: def aitchison_aitken_reg(h, Xi, x):
      """
      A version for the Aitchison-Aitken kernel for nonparametric regression.
  
      Suggested by Li and Racine.
      """
      kernel_value = np.ones(Xi.size)
      ix = Xi != x
      inDom = ix * h
      kernel_value[ix] = inDom[ix]
      return kernel_value
  
file_path: statsmodels/statsmodels/nonparametric/kernels.py
imports: import numpy
  from scipy.special import erf
label_desc: Use image node_id 12 for calling a global function with example usage: aitchison_aitken_reg(h, Xi, x) and returns: kernel_value