code: def child_U(self):
      return (
          math.sqrt(self.number_visits)
          * self.child_priors
          / (1 + self.child_number_visits)
      )
  
imports: import collections
  import copy
  import math
  import numpy
label_desc: Use image node_id 7 for calling the Node obj's underlying member method code with example usage: obj.child_U() and returns: unknown