scrapy/scrapy — pull request #497 by kmike (2013-12-19 09:13:26+00:00)
Title: [MRG] no need to use dict in scrapy.utils.python.unique

We don't support Python 2.2 anymore :)

There are other possible optimizations (like special-casing identity key function), but `scrapy.utils.python.unique` is barely used in scrapy, and all usages in scrapy are with non-default key function.