dir(version=Version('2.7'))
        '/usr/lib/python2.7/dist-packages/'
        >>> i.sitedir(version='3.1', gdb=True, package='python3-foo')
        'debian/python3-foo/usr/lib/debug/usr/lib/python3/dist-packages/'
        >>> i.sitedir(version=Version('3.2'))
        '/usr/lib/python3/dist-packages/'
        >>> Interpreter('pypy').sitedir(version='2.0')
        '/usr/lib/pypy/dist-packages/'
        r"