class_docstr: It represents the relationship between two items.
class_docstr_tok: ["It","represents","the","relationship","between","two","items","."]
code: def __str__(self):
      return "Relation [id1: %s, id2: %s, label: %s]" % (
          self.id1,
          self.id2,
          self.label,
      )
  
imports: from bigdl.util.common import *
  from zoo.common.utils import callZooFunc
  from bigdl.dataset.dataset import DataSet
  from pyspark.serializers import CloudPickleSerializer
  import sys
  import math
  import warnings
label_desc: Use image node_id 3 for calling the Relation obj's underlying member method code with example usage: obj.__str__() and returns: unknown