code: def _local_simple_mean(X, train_length):
      res = np.zeros(len(X) - train_length)
      for i in range(len(res)):
          nsum = 0
          for n in range(train_length):
              nsum += X[i + n]
          res[i] = X[i + train_length] - nsum / train_length
      return res
  
imports: import math
  import numpy
  from sktime.utils.numba.njit import njit
label_desc: Use image node_id 9 for calling a global function with example usage: _local_simple_mean(X, train_length) and returns: res