How do I embed a single file from a GitHub gist that include multiple files?

I had to look again for it so let me document it here. How do I embed a single file from a GitHub gist that include multiple files?

Question: How do I embed a single file from a GitHub gist that include multiple files?

Answer

Append to the url ?file=filename_with_ext 

Example:

<script src="https://gist.github.com/tdalon/8d396639c43bc2100224df00a5f84c7d.js?file=Outlook_Item2Emails.ahk"></script>

will render:

The gist include multiple files.

Source: How do I embed a single file from a GitHub gist with the new gist interface? - Stack Overflow