public function testPipelineWorkflow()
{
$transformers = [new Imputer(null, new MostFrequentStrategy()), new Normalizer()];
$estimator = new SVC();
$samples = [[1, -1, 2], [2, 0, null], [null, 1, -1]];
$targets = [4, 1, 4];
$pipeline = new Pipeline($transformers, $estimator);
$pipeline->train($samples, $targets);
$predicted = $pipeline->predict([[0, 0, 0]]);
$this->assertEquals(4, $predicted[0]);
}