proc default_int_handler(signalnum: int; frame: PFrame) {.
    ...raises: [KeyboardInterrupt], tags: [], forbids: [].}

proc set_wakeup_signal(signalnum: int): int {....raises: [], tags: [], forbids: [].}

proc signal(signalnum: int; handler: CSigHandler | NimSigHandler | Handlers): PySigHandler {.
    discardable.}

proc signal(signalnum: int; handler: PySigHandler): PySigHandler {.discardable,
    ...raises: [ValueError, PyOSError], tags: [], forbids: [].}