This should be `fabtools.arch.install(...)` (not `deb`).

Also, the example should use a package name relevant for Archlinux users. `build-essential` is Debian specific. The Archlinux equivalent is `base-devel` but is already part of the base install, so maybe use something else.

Also make sure that python-dev' and 'libxml2-dev' (used below) are valid Archlinux package names.