code: def xmoe_2d_x64():
      """Two-dimensional hierarchical mixture of 64 experts."""
      hparams = xmoe_2d()
      # hparams.mesh_shape = "b0:4;b1:8"
      hparams.outer_batch_size = 4
      hparams.moe_num_experts = [8, 8]
      return hparams
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from tensor2tensor.models import mtf_transformer
  from tensor2tensor.models import mtf_transformer2
  from tensor2tensor.models.research import moe
  from tensor2tensor.utils import registry
label_desc: Use image node_id 13 for calling a global function with example usage: xmoe_2d_x64() and returns: hparams