Vim: Set vim filetype to ruby in a Treetop grammar file

While writing a syntax parser using ruby treetop library for a work project I discovered the need to use ruby filetype for syntax highlighting etc a file ending in .treetop (treetop uses polyglot to look for and compile the grammar on runtime but the grammar file has to end in .treetop).

Here is a nice getting started tutorial for treetop:

I could have used some configuration in my .vimrc file to associate this file extension with ruby filetype but I want to try the embedded configuration which I have seen other used but never used myself.

After some search I found the reference article below and was by just adding the following file in the .treetop file I was able to desired functionality:

# vim:filetype=ruby

Ref:Embedding vim Settings in the File You’re Editing