
  -spec erlang:crc32_combine(FirstCrc, SecondCrc, SecondSize) ->
                                non_neg_integer()
                                when
                                    FirstCrc :: non_neg_integer(),
                                    SecondCrc :: non_neg_integer(),
                                    SecondSize :: non_neg_integer().

  Combines two previously computed crc32 checksums. This computation
  requires the size of the data object for the second checksum to be
  known.

  The following code:

    Y = erlang:crc32(Data1),
    Z = erlang:crc32(Y,Data2).

  assigns the same value to Z as this:

    X = erlang:crc32(Data1),
    Y = erlang:crc32(Data2),
    Z = erlang:crc32_combine(X,Y,iolist_size(Data2)).
