_:na1d8f168077a434daa63999ba802b8dcxb4
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.khanacademy.org/math/math2/xe2ae2386aa2e13d6:complex/xe2ae2386aa2e13d6:complex-num-intro/a/intro-to-complex-numbers>