update

        # OpenSSL::HMAC.update

(from ruby core)
### Implementation from HMAC
---
    hmac.update(string) -> self

---

Returns *hmac* updated with the message to be authenticated. Can be
called repeatedly with chunks of the message.

### Example

    first_chunk = 'The quick brown fox jumps '
    second_chunk = 'over the lazy dog'

    instance.update(first_chunk)
    #=> 5b9a8038a65d571076d97fe783989e52278a492a
    instance.update(second_chunk)
    #=> de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9