class_docstr: Represent the prediction results of user-item pairs.
  
  Each prediction record will contain the following information:
  user_id: Positive int.
  item_id: Positive int.
  prediction: The prediction (rating) for the user on the item.
  probability: The probability for the prediction.
class_docstr_tok: ["Represent","the","prediction","results","of","user-item","pairs",".","Each","prediction","record","will","contain","the","following","information",":","user_id",":","Positive","int",".","item_id",":","Positive","int",".","prediction",":","The","prediction","(","rating",")","for","the","user","on","the","item",".","probability",":","The","probability","for","the","prediction","."]
code: def __str__(self):
      return (
          "UserItemPrediction [user_id: %s, item_id: %s, prediction: %s, probability: %s]"
          % (
              self.user_id,
              self.item_id,
              self.prediction,
              self.probability,
          )
      )
  
imports: import sys
  from pyspark import RDD
  from zoo.models.common import *
  from zoo.common.utils import callZooFunc
label_desc: Use image node_id 3 for calling the UserItemPrediction obj's underlying member method code with example usage: obj.__str__() and returns: unknown