let hg18 =
    let hg18_url =
      "ftp://gsapubftp-anonymous@ftp.broadinstitute.org/bundle/2.8/hg18/Homo_sapiens_assembly18.fasta.gz" in
    let dbsnp_hg18_url =
      "ftp://gsapubftp-anonymous@ftp.broadinstitute.org/bundle/2.8/hg18/dbsnp_138.hg18.vcf.gz" in
    create Name.hg18
      ~metadata:"Provided by the Biokepi library"
      ~major_contigs:major_contigs_hg_family
      ~fasta:Location.(url hg18_url|> gunzip)
      ~dbsnp:Location.(url dbsnp_hg18_url |> gunzip)