title: How to define "a" predicate using rdflib.js
body: <p>I'm using <a href="https://github.com/linkeddata/rdflib.js/" rel="nofollow noreferrer">rdflib.js</a> library to generate RDF documents.
  You can define a statement in following way:</p>
  <pre><code>let subject = rdf.sym(location + '#this');
  let predicate = rdf.sym(DC('author'));
  let object = rdf.sym(authorWebId);
  statement = rdf.st(subject, predicate, object, chatDocument);
  </code></pre>
  <p>However, I couldn't find a way to define the &quot;<strong>a</strong>&quot; predicate (without quotes), i.e. I'd like to have such statement:</p>
  <pre><code>someSubject: a ldp:BasicContainer
  </code></pre>
  <p>How to define that with rdflib.js?</p>