Two links
I got this from a couple of tweets of my friend Maykel Moya ( http://twitter.com/maykelmoya ): ack is a tool like grep, aimed at programmers with large trees of heterogeneous source code. ack is written purely in Perl, and takes advantage of the power of Perl's regular expressions. http://betterthangrep.com/ Are two different references to the same integer value the same object? The answer: sometimes. Python gotcha: Bizarre integer equality