Prepend 0 to a single digit if it leads, ends, or exists in the middle of a string separate from another character
<p>Examples of "sentences" that would require a prepend of 0:</p>

<p><code>5 this is 3</code> becomes <code>05 this is 03</code></p>

<p><code>44 this is 2</code> becomes <code>44 this is 02</code> (note 44 is not prepended because it is not a single digit)</p>

<p><code>this 4 is</code> becomes <code>this 04 is</code></p>

<hr>

<p>Examples of "sentences" that would not get a prepend of 0:</p>

<p><code>44 this is</code></p>

<p><code>22 this3 is</code> (note 3 is not prepended because it exists as part of a string)</p>

<p><code>this is5</code></p>

<p>I tried coming up with a regex and failed miserably.</p>
