docs: def _read_dna(self, l, lowercase=False):
          """
          Read DNA from a 2bit file where each base is encoded in 2bit 
          (4 bases per byte).
          
          Parameters
          ----------
          l : tuple
              Location tuple
          
          Returns
          -------
          list
              Array of base chars
          """
          
          file = os.path.join(self.dir, l.chr + ".dna.2bit")
          
          print(file)
          
          if not os.path.exists(file):
              return bytearray([])
         
          f = open(file, 'rb')
          f.seek((l.start - 1) // 4)
          # read bytes into buffer
          data = f.read(l.length // 4 + 2)
          f.close()
          
          return DNA2Bit._read2bit(data, l)