code: def make_fasta_dna_url(
          ensembl_release,
          species,
          contig,
          server=ENSEMBL_FTP_SERVER):
      
      ensembl_release, species, _ = \
          normalize_release_properties(ensembl_release, species)
      subdir = _species_subdir(
          ensembl_release,
          species=species,
          filetype="fasta",
          server=server,)
      server_subdir = urllib_parse.urljoin(server, subdir)
      server_sequence_subdir = join(server_subdir, "dna")
      filename = make_fasta_dna_filename(
          ensembl_release=ensembl_release,
          species=species,
          contig=contig)
      return join(server_sequence_subdir, filename)
docs: Construct URL to FASTA file with full sequence of a particular chromosome.
      Returns server_url/subdir and filename as tuple result.