code: def xmoe_2d_c15():
      """Mixture of experts."""
      hparams = xmoe_2d()
      hparams.moe_capacity_factor_train = 1.5
      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 12 for calling a global function with example usage: xmoe_2d_c15() and returns: hparams