parse rRNA to gff format

def parse_rRNA(insertion, seq, gff):
    """
    parse rRNA to gff format
    """
    offset = insertion['offset']
    strand = insertion['strand']
    for rRNA in parse_masked(seq, 0)[0]:
        rRNA = ''.join(rRNA)
        Start = seq[1].find(rRNA) + 1
        End = Start + len(rRNA) - 1
        if strand == '-':
            Start, End = End - 2, Start - 2
        pos = (abs(Start + offset) - 1, abs(End + offset) - 1)
        Start, End = min(pos), max(pos)
        source = insertion['source']
        annot = '%s rRNA' % (source.split('from', 1)[0])
        gff['#seqname'].append(insertion['ID'])
        gff['source'].append(source)
        gff['feature'].append('rRNA')
        gff['start'].append(Start)
        gff['end'].append(End)
        gff['score'].append('.')
        gff['strand'].append(strand)
        gff['frame'].append('.')
        gff['attribute'].append('Name=%s' % (annot))
    return gff