code: def pack_results(measurements: Sequence[Tuple[str, np.ndarray]]) -> bytes:
      
      if not measurements:
          return b''
  
      shapes = [(key, np.shape(data)) for key, data in measurements]
      if not all(len(shape) == 2 for _, shape in shapes):
          raise ValueError("Expected 2-D data: shapes={}".format(shapes))
  
      reps = shapes[0][1][0]
      if not all(shape[0] == reps for _, shape in shapes):
          raise ValueError(
              "Expected same reps for all keys: shapes={}".format(shapes))
  
      bits = np.hstack([np.asarray(data, dtype=bool) for _, data in measurements])
      bits = bits.reshape(-1)
  
      # Pad length to multiple of 8 if needed.
      remainder = len(bits) % 8
      if remainder:
          bits = np.pad(bits, (0, 8 - remainder), 'constant')
  
      # Pack in little-endian bit order.
      bits = bits.reshape((-1, 8))[:, ::-1]
      byte_arr = np.packbits(bits, axis=1).reshape(-1)
  
      return byte_arr.tobytes()
docs: Pack measurement results into a byte string.
  
      Args:
          measurements: A sequence of tuples, one for each measurement, consisting
              of a string key and an array of boolean data. The data should be
              a 2-D array indexed by (repetition, qubit_index). All data for all
              measurements must have the same number of repetitions.
  
      Returns:
          Packed bytes, as described in the unpack_results docstring below.
  
      Raises:
          ValueError if the measurement data do not have the compatible shapes.