code: def testInitialization(self):
      with self.assertRaisesRegex(
          ValueError, "at least two objectives"
      ):
          DummyScalarizer(1)
      with self.assertRaisesRegex(
          ValueError, "at least two objectives"
      ):
          DummyScalarizer(0)
      with self.assertRaisesRegex(
          ValueError, "at least two objectives"
      ):
          DummyScalarizer(-1)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import copy
  import tensorflow.compat.v2
  from tf_agents.bandits.multi_objective import multi_objective_scalarizer
label_desc: Use image node_id 1 for calling the BaseScalarizerTest obj's underlying member method code with example usage: obj.testInitialization() without return types