
  -spec erlang:adler32(OldAdler, Data) -> non_neg_integer()
                          when
                              OldAdler :: non_neg_integer(),
                              Data :: iodata().

  Continues computing the adler32 checksum by combining the previous
  checksum, OldAdler, with the checksum of Data.

  The following code:

    X = erlang:adler32(Data1),
    Y = erlang:adler32(X,Data2).

  assigns the same value to Y as this:

    Y = erlang:adler32([Data1,Data2]).
