MLLinearRegressor: Setting the validation set to "None"

Hello,

if I want to set the validation set for a linear regressor to 'None', then currently it appears that this is the code to use:

        var parameters = MLLinearRegressor.ModelParameters()
        parameters.validationData = MLDataTable()

Is this the indented way, or am I overlooking something here? Setting validationData to nil will make the regressor automatically create a validation set, as if no parameters have been passed.

Personally, I think an enum would make it a lot clearer.

        enum validatationData {
            case none
            case auto
            case set (MLDataTable)
        }

Any thoughts?