code: def mean_stderr(arr):
      return sample_stddev(arr) / math.sqrt(len(arr))
  
imports: import math
  from collections.abc import Iterable
  import numpy
  import sacrebleu
  import sklearn.metrics
  import random
  from collections import defaultdict
label_desc: Use image node_id 4 for calling a global function with example usage: mean_stderr(arr) and returns: unknown