<https://blog.arduino.cc/2010/12/03/make-your-own-solenoids-and-play-xylophone-2/#breadcrumb>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://blog.arduino.cc/2010/12/03/make-your-own-solenoids-and-play-xylophone-2/>