Vim: Using Ruby Regular Expression

I needed to remove line number from a web copy-pasted code snippet. I know there is a way to configure vim to use the perl style regular expressions but I couldn’t find how quickly.

What I found was:
http://vim.wikia.com/wiki/Perl_compatible_regular_expressions

:rubydo gsub /pattern/,'replacement'</code>

Here is my specific command:

:rubydo gsub /^\s+\d{0,3}\s/, ''

Pre-requisite: look for +ruby in :ver output (if it is -ruby then it would not work).

The above web page also talks about Perl regular expression in Vim and different ways to do that.