def add_or_update(self, section, key, value):
updates = self.update(section, key, value)<EOL>if updates == <NUM_LIT:0>:<EOL><INDENT>self.add(section, key, value)<EOL><DEDENT>return updates<EOL>
Update the key or, if no previous value existed, add it.

        Returns:
            int: Number of updated lines.