Add a FILTER value to a cyvcf2 record

def cyvcf_add_filter(rec, name):
    """Add a FILTER value to a cyvcf2 record
    """
    if rec.FILTER:
        filters = rec.FILTER.split(";")
    else:
        filters = []
    if name not in filters:
        filters.append(name)
        rec.FILTER = filters
    return rec