def writeScwrlSequenceFile(sequence, filename='x-ray.seq', options=None):
    """
    writing a scwrl sequence file for, e.g.,  generating a mutated protein
    """
    file = open(filename, 'w')
    start = 0
    while len(sequence[start:]) > 60:
        file.write('%s\n' % sequence[start:start + 60])
        start += 60
    file.write('%s\n' % sequence[start:])
    file.close()
