Find function and line number where variable gets modified
<p>Let's say that at the beginning of a random function variable $variables['content'] is 1,000 characters long.</p>

<p>This random function is very long, with many nested functions within.</p>

<p>At the end of the function $variables['content'] is only 20 characters long. </p>

<p>How do you find which of nested functions modified this variable?</p>
