'Return a `ImportTask` with all media files from paths.
`dirs` is a list of parent directories used to record already
imported albums.'

def album(self, paths, dirs=None):

    if (not paths):
        return None
    if (dirs is None):
        dirs = list(set((os.path.dirname(p) for p in paths)))
    if self.session.already_imported(self.toppath, dirs):
        log.debug(u'Skipping    previously-imported    path:    {0}', displayable_path(dirs))
        self.skipped += 1
        return None
    items = map(self.read_item, paths)
    items = [item for item in items if item]
    if items:
        return ImportTask(self.toppath, dirs, items)
    else:
        return None
