def platform(cls):
        """
        What Operating System (and sub-system like glibc / musl)
        """
        system_name = platform.system()
        if system_name == "Linux":
            libc = cls.libc()
            return "unknown-linux-{libc}".format(libc=libc)
        elif system_name == "Darwin":
            return "apple-darwin"
        else:
            return "unknown"