code: def make_transcript_gene_se(fn):
      
      import itertools as it
  
      import HTSeq
  
      gtf = it.islice(HTSeq.GFF_Reader(fn), None)
      transcripts = []
      genes = []
      line = gtf.next()
      while line != '':
          if line.type == 'transcript':
              transcripts.append(line.attr['transcript_id'])
              genes.append(line.attr['gene_id'])
          try:
              line = gtf.next()
          except StopIteration:
              line = ''
     
      return pd.Series(genes, index=transcripts)
docs: Make a Pandas Series with transcript ID's as the index and values as the
      gene ID containing that transcript.
  
      Parameters
      ----------
      fn : str
          Filename of the Gencode gtf file.
  
      Returns
      -------
      se : pandas.Series
          Make a Pandas Series with transcript ID's as the index and values as the
          gene ID containing that transcript.