'Returns the total size of the content in the torrent. If the
optional selectedfiles argument is specified, the method returns
the total size of only those files.
@return A length (long)'

def get_length(self, selectedfiles=None):

    if (not self.metainfo_valid):
        raise NotYetImplementedException()
    return maketorrent.get_length_from_metainfo(self.metainfo, selectedfiles)
