To judge from the source, attributes in the py namespace are dynamically created, and this is why pylint, a static analysis tool, is unable to recognise them:

apipkg.initpkg(__name__, attr={'_apipkg': apipkg}, exportdefs={
    ...
    # small and mean xml/html generation
    'xml' : {
        '__doc__'            : '._xmlgen:__doc__',
        'html'               : '._xmlgen:html',
        'Tag'                : '._xmlgen:Tag',
        'raw'                : '._xmlgen:raw',
        'Namespace'          : '._xmlgen:Namespace',
        'escape'             : '._xmlgen:escape',
    },
})

If pylint compliance is a requirement for your project then you will need to get agreement that warnings for these imports can be ignored.