<https://forum.digilentinc.com/topic/17794-use-4x4-keypad-using-jb-pmod-port-of-basys3-fpga/>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://forum.digilentinc.com/topic/17794-use-4x4-keypad-using-jb-pmod-port-of-basys3-fpga/#comment-45421>