code: def pop_stddev(arr):
      mu = mean(arr)
      return math.sqrt(sum([(x - mu) ** 2 for x in arr]) / 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 2 for calling a global function with example usage: pop_stddev(arr) and returns: math