Update example

main.py

@@ -3,10 +3,11 @@ import subprocess
 import tempfile
 from pathlib import Path
 
-EXAMPLE_CODE = """int main() {
-    x = 10;
-    y = foo(x);
-    return y;
+EXAMPLE_CODE = """void f()
+{
+    T v = 0;
+    v->value = 42;
+    v->next = v;
 }"""
 
 def run_psychec(c_code: str):