code: def get_chromosome_priority(chrom, chrom_dict={}):
      
      priority = 0
      
      chrom = str(chrom).lstrip('chr')
      
      if chrom_dict:
          priority = chrom_dict.get(chrom, 0)
      
      else:
          try:
              if int(chrom) < 23:
                  priority = int(chrom)
          except ValueError:
              if chrom == 'X':
                  priority = 23
              elif chrom == 'Y':
                  priority = 24
              elif chrom == 'MT':
                  priority = 25
              else:
                  priority = 26
      
      return str(priority)
docs: Return the chromosome priority
      
      Arguments:
          chrom (str): The cromosome name from the vcf
          chrom_dict (dict): A map of chromosome names and theis priority
      
      Return:
          priority (str): The priority for this chromosom