code: def _FC_LocalSimple_mean3_stderr(X):
      # Mean error from a rolling 3-sample mean forecasting.
      if len(X) - 3 < 3:
          return 0
      res = _local_simple_mean(X, 3)
      return np.std(res)
  
imports: import math
  import numpy
  from sktime.utils.numba.njit import njit
label_desc: Use image node_id 24 for calling a global function with example usage: _FC_LocalSimple_mean3_stderr(X) and returns: np, int