code: def makeChromID(chrom, reference=None, prefix=None):
      
      # blank nodes
      if reference is None:
          LOG.warning('No reference for this chr. You may have conflicting ids')
  
      # replace any chr-like prefixes with blank to standardize
      chrid = re.sub(r'ch(r?)[omse]*', '', str(chrom))
  
      # remove the build/taxon prefixes to look cleaner
      ref = reference
      if re.match(r'.+:.+', reference):
          ref = re.match(r'.*:(.*)', reference).group(1)
      chrid = ''.join((ref, 'chr', chrid))
      if prefix is None:
          chrid = ''.join(('_', chrid))
      else:
          chrid = ':'.join((prefix, chrid))
  
      return chrid
docs: This will take a chromosome number and a NCBI taxon number,
      and create a unique identifier for the chromosome.  These identifiers
      are made in the @base space like:
      Homo sapiens (9606) chr1 ==> :9606chr1
      Mus musculus (10090) chrX ==> :10090chrX
  
      :param chrom: the chromosome (preferably without any chr prefix)
      :param reference: the numeric portion of the taxon id
  
      :return: