class_docstr: Micro-cluster class.
code: def _deviation(self):
      dev_sum = 0
      for var in self.var_x.values():
          dev_sum += math.sqrt(var.get())
      return (
          dev_sum / len(self.var_x) if len(self.var_x) > 0 else math.inf
      )
  
imports: from __future__ import annotations
  import math
  from collections import defaultdict
  from river import base, cluster, stats, utils
label_desc: Use image node_id 4 for calling the CluStreamMicroCluster obj's underlying member method code with example usage: obj._deviation() and returns: unknown