in tensorflow/src/main/scala/magnolify/tensorflow/ExampleType.scala [257:265]
override def get(fs: Map[String, Feature], k: String)(cm: CaseMapper): Option[T] =
if (fs.isEmpty) None else Some(ef.get(fs, k)(cm))
override def put(f: Features.Builder, k: String, v: Option[T])(
cm: CaseMapper
): Features.Builder = v match {
case None => f
case Some(x) => ef.put(f, k, x)(cm)
}