input: from typing import List
  
  
  def calculate_rRNA_percentage(htseq_counts: str, gtf_file: str) -> List[float]:
      """ Calculate the percentage of transcripts in an HTseq_counts file that map to rRNA and MT genes, given a GTF file.
      Return a list containing two percentages: the percentage of rRNA transcripts and the percentage of MT transcripts.
      >>> calculate_rRNA_percentage('C17_3_S20_Aligned.out.srt.bam_htseq_combined_counts.txt', '/Users/malwina/Documents/CTR-Data/genomes/Mus_musculus/mm10/Mus_musculus.GRCm38.84.gtf')
      [0.123, 0.456]
      """
output:     
      rRNA_count = 0
      MT_count = 0
      total_count = 0
      
      # Read the GTF file to identify rRNA and MT genes
      rRNA_genes = set()
      MT_genes = set()
      
      with open(gtf_file, 'r') as gtf:
          for line in gtf:
              if line.startswith('#'):
                  continue
              fields = line.strip().split('\t')
              if fields[2] == 'gene':
                  gene_info = fields[8]
                  if 'gene_biotype "rRNA"' in gene_info:
                      gene_name = gene_info.split('gene_name "')[1].split('";')[0]
                      rRNA_genes.add(gene_name)
                  elif 'gene_biotype "Mt_rRNA"' in gene_info or 'gene_biotype "Mt_tRNA"' in gene_info:
                      gene_name = gene_info.split('gene_name "')[1].split('";')[0]
                      MT_genes.add(gene_name)
      
      # Read the HTseq_counts file to count rRNA and MT transcripts
      with open(htseq_counts, 'r') as htseq:
          for line in htseq:
              if line.startswith('__'):
                  continue
              gene_name, count = line.strip().split('\t')
              count = int(count)
              total_count += count
              if gene_name in rRNA_genes:
                  rRNA_count += count
              elif gene_name in MT_genes:
                  MT_count += count
      
      # Calculate the percentages
      rRNA_percentage = rRNA_count / total_count * 100
      MT_percentage = MT_count / total_count * 100
      
      return [rRNA_percentage, MT_percentage]
  