title: .call(this) idiom in JavaScript
body: <p>In some JavaScript I see:</p>
  
  <pre><code>var passport = require('passport')
  
  function Strategy(options, verify) {
    //...
  
    passport.Strategy.call(this);
  }
  </code></pre>
  
  <p>What is <code>passport.Strategy.call(this);</code> doing?</p>