title: Make functional functions OO functions in Javascript
body: <p>Let's say I have this easy <code>id</code> function:</p>
  
  <pre><code>let id = a =&gt; a
  </code></pre>
  
  <p>And now I want to make it a OO-style method, without redefining it, i.e.</p>
  
  <pre><code>let a = {foo:5}
  a.id()  // {foo:5}
  </code></pre>
  
  <p>How can I turn the first function into the second? Is there some hack to do this? I tried working with <code>bind</code>, but it didn't seem to work.</p>