public void AppendPipeline()
        {
            var pipeline = new Legacy.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);
        }