def save_pair(connection, digest, word):
    """Save both the original word and its digest into the database.

  Parameters:
    - connection: The connection to the SQLite database.
    - digest: The digest of the plaintext word; acts as the primary key.
    - word: The plaintext word.

  """
    cursor = connection.cursor()
    _t = digest, word
    cursor.execute("""INSERT INTO rainbow
    VALUES (NULL, ?, ?)""", _t)
    connection.commit()
