code: func (step *CallFlowTransferStep) MarshalJSON() ([]byte, error) {
  	data := jsonCallFlowTransferStep{}
  	data.CallFlowStepBase = step.CallFlowStepBase
  	data.Action = "transfer"
  	data.Options.Destination = step.Destination
  	data.Options.Record = step.Record
  	return json.Marshal(data)
  }
docs: // MarshalJSON implements the json.Marshaler interface.