Return breakend information line with mate and imprecise location.

def _vcf_info(start, end, mate_id, info=None):
    """Return breakend information line with mate and imprecise location.
    """
    out = "SVTYPE=BND;MATEID={mate};IMPRECISE;CIPOS=0,{size}".format(
        mate=mate_id, size=end-start)
    if info is not None:
        extra_info = ";".join("{0}={1}".format(k, v) for k, v in info.iteritems())
        out = "{0};{1}".format(out, extra_info)
    return out