* string|null function ( string $message, string $level, array $context );
* @param bool $collectContext Whether to keep the context passed to log
* (since 1.29, @see setCollectContext()).
* string|null function ( string $message, string $level, array $context );
* @param bool $collectContext Whether to keep the context passed to log
* (since 1.29, @see setCollectContext()).