input: 
  def calculate_rrna_percentage(htseq_counts_file: str, gtf_file: str) -> str:
      """ Calculate the percent of transcripts mapping to rRNA and MT using the provided HTseq_counts file and GTF file.
      >>> calculate_rrna_percentage("/path/to/HTseq_counts/file", "/path/to/GTF/file")
      "Summary output file: HTseq_counts_file_rRNAmtRNACounts.txt"
      """
  
output:     rrna_mt_counts = 0
      total_counts = 0
  
      with open(htseq_counts_file, 'r') as htseq_file:
          for line in htseq_file:
              if not line.startswith("__"):
                  gene_id, count = line.strip().split('\t')
                  total_counts += int(count)
  
      with open(gtf_file, 'r') as gtf_file:
          for line in gtf_file:
              if not line.startswith("#"):
                  fields = line.strip().split('\t')
                  if fields[2] == "gene":
                      gene_info = fields[8]
                      if "gene_biotype \"rRNA\"" in gene_info or "gene_biotype \"Mt_rRNA\"" in gene_info:
                          gene_id = gene_info.split(';')[0].split()[1].strip('"')
                          with open(htseq_counts_file, 'r') as htseq_file:
                              for htseq_line in htseq_file:
                                  if htseq_line.startswith(gene_id):
                                      rrna_mt_counts += int(htseq_line.strip().split('\t')[1])
  
      rrna_mt_percentage = (rrna_mt_counts / total_counts) * 100
      output_file_name = htseq_counts_file.replace(".txt", "_rRNAmtRNACounts.txt")
  
      with open(output_file_name, 'w') as output_file:
          output_file.write(f"rRNA and MT counts: {rrna_mt_counts}\n")
          output_file.write(f"Total counts: {total_counts}\n")
          output_file.write(f"Percentage of rRNA and MT: {rrna_mt_percentage:.2f}%\n")
  
      return f"Summary output file: {output_file_name}"