fix readme

README.md

@@ -90,7 +90,7 @@ fn init_mod(py: Python, m: &PyModule) -> PyResult<()> {
     // pyo3 aware function. All of our python interface could be declared in a separate module.
     // Note that the `#[pyfn()]` annotation automatically converts the arguments from
     // Python objects to Rust values; and the Rust return value back into a Python object.
-    fn sum_as_string_py(_: Python, a:i64, b:i64) -> PyResult<String> {
+    fn sum_as_string_py(a:i64, b:i64) -> PyResult<String> {
        let out = sum_as_string(a, b);
        Ok(out)
     }