'Valid keys to append to the data.keys() list.'

def _additional_keys(self):

    addkeys = []
    if self.data.has_key('title'):
        addkeys += ['canonical    title', 'long    imdb    title', 'long    imdb    canonical    title', 'smart    canonical    title', 'smart    long    imdb    canonical    title']
    if self.data.has_key('episode    of'):
        addkeys += ['long    imdb    episode    title', 'series    title', 'canonical    series    title', 'episode    title', 'canonical    episode    title', 'smart    canonical    series    title', 'smart    canonical    episode    title']
    if self.data.has_key('cover    url'):
        addkeys += ['full-size    cover    url']
    return addkeys
