code: func (t *Trainer) Cost() <-chan float64 {
  	if t.cost == nil {
  		t.cost = make(chan float64)
  	}
  	return t.cost
  }
docs: /* Getters */
  // Cost returns a channel of costs for monitoring the training. If the PassDirect field in the trainer is set to true
  // then the costs are directly returned. Otherwise the costs are averaged over the epoch.