code: def create_mean(self):
      return MultitaskMean(
          [
              ConstantMean(batch_shape=torch.Size([3])),
              ZeroMean(),
              ZeroMean(),
          ],
          num_tasks=3,
      )
  
imports: import unittest
  import torch
  from gpytorch.means import ConstantMean, MultitaskMean, ZeroMean
  from gpytorch.test.base_mean_test_case import BaseMeanTestCase
label_desc: Use image node_id 1 for calling the TestMultitaskMeanBatch obj's underlying member method code with example usage: obj.create_mean() and returns: MultitaskMean