chore: checkpoint before Python removal

vendor/unsafe-libyaml/src/success.rs

@@ -0,0 +1,25 @@
+use core::ops::Deref;
+
+pub const OK: Success = Success { ok: true };
+pub const FAIL: Success = Success { ok: false };
+
+#[must_use]
+pub struct Success {
+    pub ok: bool,
+}
+
+pub struct Failure {
+    pub fail: bool,
+}
+
+impl Deref for Success {
+    type Target = Failure;
+
+    fn deref(&self) -> &Self::Target {
+        if self.ok {
+            &Failure { fail: false }
+        } else {
+            &Failure { fail: true }
+        }
+    }
+}