The initial poster posted this link: https://github.com/paritytech/parity/blob/master/js/src/cont...
Where "master" is the branch which normally has the latest code. And #L216 automatically scrolls down to the 216th line.
The issue is that line isn't permanent since the code in the master branch is subject to change. So in order to make a reliable link, you can link to the ref [1].
Like this: https://github.com/paritytech/parity/blob/4c32177ef3f4521c66...
You could also do it with the short ref (4c32177e): https://github.com/paritytech/parity/blob/4c32177e/js/src/co...
Normally you'd have to scroll up to the top right of the document and grab the short form it, e.g. "6b0e4f9" and replace it with master. Note that's only the ref of the last change for that blob (file) [2].
If you click the line number on a GitHub file, it will add the #LineNumber to your URL.
From there, press Y, this will replace master with the latest commit of the repo.
[1] https://git-scm.com/book/en/v2/Git-Internals-Git-References
[2] https://git-scm.com/book/en/v2/Git-Internals-Git-Objects
Based on the time of your post, I suspect you meant to link to:
https://github.com/paritytech/parity/blob/4c32177ef3f4521c66...