ENV.clone

static VALUE
env_clone(int argc, VALUE *argv, VALUE obj)
{
    if (argc) {
        VALUE opt, kwfreeze;
        if (rb_scan_args(argc, argv, "0:", &opt) < argc) {
            kwfreeze = rb_get_freeze_opt(1, &opt);
            if (RTEST(kwfreeze)) {
                rb_raise(rb_eTypeError, "cannot freeze ENV");
            }
        }
    }

    rb_warn_deprecated("ENV.clone", "ENV.to_h");
    return envtbl;
}