public void AppendPipeline()
{
var pipeline = new LearningPipeline();
pipeline.Append(new CategoricalOneHotVectorizer("String1", "String2"))
.Append(new ColumnConcatenator(outputColumn: "Features", "String1", "String2", "Number1", "Number2"))
.Append(new StochasticDualCoordinateAscentRegressor());
Assert.NotNull(pipeline);
Assert.Equal(3, pipeline.Count);
pipeline.Remove(pipeline.ElementAt(2));
Assert.Equal(2, pipeline.Count);
pipeline.Append(new StochasticDualCoordinateAscentRegressor());
Assert.Equal(3, pipeline.Count);
}