 4     # letter &#x27;O&#x27; or number 0?
l = l + 5     # letter &#x27;l&#x27; or number 1?</code></pre>


        <h3 id="unnecessary-variables">Unnecessary variables</h3>


        <p>Don't create unnecessary variables. For example,</p>

        <blockquote>
          <p>Good</p>
        </blockquote>

        <pre><code>return answer(argument)</code></pre>

        <blockquote>
          <p>Bad</p>
        </blockquote>

        <pre><code>result = answer(argument)
return result</code></pre>

        <p