Booking.com Perl Developer interview questions

Replied to a post on Hacker News via email. The guy was very friendly and forwarded my resume to HR which scheduled a technical phone interview in 20 days based on my preference, again via email. On the phone interview, i was asked to describe my perl proficiency level on a scale from 1 to 10. The interviewer started with Perl related questions, then switched to general programming questions, then sql questions, and finally switched to business related dev questions, all based on my performance in the previous sections.