code: func (mc MongoClient) AddTransmission(t contract.Transmission) (string, error) {
  	s := mc.getSessionCopy()
  	defer s.Close()
  
  	var mapped models.Transmission
  	id, err := mapped.FromContract(t)
  	if err != nil {
  		return "", err
  	}
  
  	mapped.TimestampForAdd()
  
  	if err = s.DB(mc.database.Name).C(TRANSMISSION_COLLECTION).Insert(mapped); err != nil {
  		return "", errorMap(err)
  	}
  
  	return id, nil
  }
docs: /* ----------------------- Transmissions ------------------------*/
  // limits for transmissions here refer to resend counts