def remove_dup_on_chrY(snp_dfm, verbose=True):
    """
        It is known that each of "rs700442", "rs5989681" and "rs4446909" has 2 entries in
        snp146, hg19 of UCSC Genome Browser, one on chrX and the other chrY.
        
        Remove the one on chrY as suggested by Steve:
        
        > I would just use the ChrX entry, for this SNP.
        > My reasoning:  we very likely don't have haplotype data for chrY.
    """
    is_dup = snp_dfm.duplicated(subset="name", keep=False)
    on_chrY = (snp_dfm.loc[:, "chrom"] == "chrY")
    
    if verbose and is_dup.any():
        print("remove_dup_on_chrY: duplication detected: \r\n%s" % snp_dfm.loc[is_dup, :])
    
    snp_dfm = snp_dfm.drop(snp_dfm[is_dup & on_chrY].index)
    
    still_dup = snp_dfm.duplicated(subset="name", keep=False)
    assert not still_dup.any(), "remove_dup_on_chrY: still duplicated after removal: \r\n%s" % snp_dfm.loc[still_dup, :]
    
    return snp_dfm