supports just the Tophat unstranded/firstrand/secondstrand

def _libtype_string(fq1, fq2, strandedness):
    """
    supports just the Tophat unstranded/firstrand/secondstrand
    """
    libtype = "-l I" if fq2 else "-l "
    strand = _sailfish_strand_string(strandedness)
    return libtype + strand