```\nfunction _setTransceiver(address transceiver) internal returns (uint8 index) {\n    /* snip */\n    if (transceiver == address(0)) {\n        revert InvalidTransceiverZeroAddress();\n    }\n\n    if (_numTransceivers.registered >= MAX_TRANSCEIVERS) {\n        revert TooManyTransceivers();\n    }\n\n    if (transceiverInfos[transceiver].registered) {\n        transceiverInfos[transceiver].enabled = true;\n    } else {\n    /* snip */\n}\n```\n