chore: checkpoint before Python removal

vendor/psm/examples/replace_stack_1.rs

@@ -0,0 +1,33 @@
+extern crate psm;
+
+psm::psm_stack_manipulation! {
+    yes {
+        use std::alloc;
+
+        const STACK_SIZE: usize = 4096 * 64;
+        const STACK_ALIGN: usize = 4096;
+
+        fn main() {
+            println!("current stack pointer is {:p}", psm::stack_pointer());
+            unsafe {
+                let new_stack = alloc::alloc(alloc::Layout::from_size_align(STACK_SIZE, STACK_ALIGN).unwrap());
+                println!("new stack is between {:p} and {:p}", new_stack, new_stack.offset(STACK_SIZE as isize));
+                psm::replace_stack(new_stack, STACK_SIZE, || {
+                    println!("after replacement stack pointer is {:p}", psm::stack_pointer());
+                    ::std::process::exit(0);
+                });
+            }
+        }
+    }
+    no {
+        fn main() {
+            eprintln!("Stack manipulation not supported by this target");
+        }
+    }
+}
+
+#[test]
+fn run_example() {
+    // NOTE: intentionally out-of-processes, as the example exits with `process::exit(0)`.
+    main()
+}