input: def calculate_rrna_percent(htseq_counts_file: str, gtf_file: str) -> dict:
      """ Calculate the percent of transcripts mapping to rRNA and MT genes from given HTseq_counts file and GTF file.
      Return a dictionary with key-value pairs for 'rRNA_percent' and 'MT_percent'.
      >>> calculate_rrna_percent('/path/to/HTseq_counts/file', '/path/to/GTF/file')
      {'rRNA_percent': 1.234, 'MT_percent': 0.456}
      """
output:     import pandas as pd
      import gtfparse
  
      # Read HTseq counts file
      htseq_counts = pd.read_csv(htseq_counts_file, sep='\t', header=None, names=['gene_id', 'count'])
  
      # Read GTF file
      gtf_df = gtfparse.read_gtf(gtf_file)
  
      # Filter rRNA and MT genes from GTF file
      rrna_genes = gtf_df[gtf_df['gene_biotype'] == 'rRNA']['gene_id'].unique()
      mt_genes = gtf_df[gtf_df['gene_biotype'] == 'Mt_rRNA']['gene_id'].unique()
  
      # Calculate total counts
      total_counts = htseq_counts['count'].sum()
  
      # Calculate rRNA and MT counts
      rrna_counts = htseq_counts[htseq_counts['gene_id'].isin(rrna_genes)]['count'].sum()
      mt_counts = htseq_counts[htseq_counts['gene_id'].isin(mt_genes)]['count'].sum()
  
      # Calculate percentages
      rrna_percent = (rrna_counts / total_counts) * 100
      mt_percent = (mt_counts / total_counts) * 100
  
      return {'rRNA_percent': rrna_percent, 'MT_percent': mt_percent}