Get the argument names of an R function : <p>For an arbitrary function </p>

<pre><code>f &lt;- function(x, y = 3){
  z &lt;- x + y
  z^2
}
</code></pre>

<p>I want to be able take the argument names of <code>f</code></p>

<pre><code>&gt; argument_names(f)
[1] "x" "y"
</code></pre>

<p>Is this possible?</p>
