code: def xmoe_top_2():
      """Mixture of experts (16 experts)."""
      hparams = xmoe_dense_4k()
      moe.set_default_moe_hparams(hparams)
      hparams.mesh_shape = "all:8"
      hparams.layout = "batch:all;experts:all"
      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 8 for calling a global function with example usage: xmoe_top_2() and returns: hparams