CairoSVG relies on cssselect to handle CSS, this ebuild should depend on the dev-python/cssselect.
However, as lxml, cssselect and tinycss are optional and only needed to handle CSS, they may be added in DEPEND/RDEPEND thanks to a use flag.
+*cairosvg-1.0 (19 Sep 2013)
+ 19 Sep 2013; Sergey Popov <firstname.lastname@example.org> -cairosvg-0.4.3.ebuild,
+ Version bump, fixes bug #421663. Migrate to distutils-r1, add
+ dev-python/cssselect as dependency, wrt bug #424812. Drop old version