code: def _make_index(self, fasta, index):
          
          out = open(index, "wb")
          f = open(fasta)
          # Skip first line of fasta-file
          line = f.readline()
          offset = f.tell()
          line = f.readline()
          while line:
              out.write(pack(self.pack_char, offset))
              offset = f.tell()
              line = f.readline()
          f.close()
          out.close()
docs: Index a single, one-sequence fasta-file