code: def unpack_binary(self, offset, length=False):
          
          if not length:
              return bytes("".encode("ascii"))
          o = self._offset + offset
          try:
              return bytes(struct.unpack_from("<{}s".format(length), self._buf, o)[0])
          except struct.error:
              raise OverrunBufferException(o, len(self._buf))
docs: Returns raw binary data from the relative offset with the given length.
          Arguments:
          - `offset`: The relative offset from the start of the block.
          - `length`: The length of the binary blob. If zero, the empty string
              zero length is returned.
          Throws:
          - `OverrunBufferException`