import fcntl

def set_close_exec(fd):
    """
    Helper to add CLOEXEC to provided file descriptor.
    :param fd: int
    """
    flags = fcntl.fcntl(fd, fcntl.F_GETFD)
    fcntl.fcntl(fd, fcntl.F_SETFD, flags | fcntl.FD_CLOEXEC)