code: def test_evaluator_name(self):
      self.evaluator.name = "eval"
      mean = self.evaluator()
      # name is used as a prefix
      self.assertAlmostEqual(
          mean["eval/main/loss"], self.expect_mean, places=4
      )
  
imports: import unittest
  import numpy
  import chainer
  from chainer import backend
  from chainer.backends import _cpu
  from chainer import dataset
  from chainer import iterators
  from chainer import testing
  from chainer.training import extensions
label_desc: Use image node_id 4 for calling the TestEvaluator obj's underlying member method code with example usage: obj.test_evaluator_name() without return types