code: def ensembl(args):
      
      p = OptionParser(ensembl.__doc__)
      p.add_option("--version", default="75",
                   help="Ensembl version [default: %default]")
      opts, args = p.parse_args(args)
  
      version = opts.version
      url = "ftp://ftp.ensembl.org/pub/release-{0}/".format(version)
      fasta_url = url + "fasta/"
  
      valid_species = [x for x in ls_ftp(fasta_url) if "." not in x]
      doc = "\n".join((ensembl.__doc__, tile(valid_species)))
      p.set_usage(doc)
  
      if len(args) != 1:
          sys.exit(not p.print_help())
  
      species, = args
      species = species.split(",")
      for s in species:
          download_species_ensembl(s, valid_species, url)
docs: %prog ensembl species
  
      Retrieve genomes and annotations from ensembl FTP. Available species
      listed below. Use comma to give a list of species to download. For example:
  
      $ %prog ensembl danio_rerio,gasterosteus_aculeatus