convert fq to fa

def fq2fa(fq):
    """
    convert fq to fa
    """
    c = cycle([1, 2, 3, 4])
    for line in fq:
        n = next(c)
        if n == 1:
            seq = ['>%s' % (line.strip().split('@', 1)[1])]
        if n == 2:
            seq.append(line.strip())
            yield seq