<i>Take notes</i> (external to the code) on everything you learn about a given module, whether code&#x2F;flow analysis, insights on input &#x2F; output &#x2F; objects, visible interactions, and what it reveals about how project-specific libraries are used.  Otherwise, it&#x27;s so easy to have an &quot;oh, <i>that&#x27;s</i> what that does&quot; insight and lose it later because you assumed you&#x27;d remember it.