Add ArgIndex according to RustPython#4629

Author: minhrongcon2000

vm/src/function/number.rs

@@ -1,5 +1,4 @@
-use crate::{AsObject, PyObjectRef, PyResult, TryFromObject, VirtualMachine};
-use num_bigint::BigInt;
+use crate::{builtins::PyIntRef, AsObject, PyObjectRef, PyResult, TryFromObject, VirtualMachine};
 use num_complex::Complex64;
 use std::ops::Deref;
 
@@ -128,20 +127,20 @@ impl TryFromObject for ArgIntoBool {
 }
 
 // Implement ArgIndex to seperate between "true" int and int generated by index
-#[derive(Debug, PartialEq)]
+#[derive(Debug)]
 #[repr(transparent)]
 pub struct ArgIndex {
-    value: BigInt,
+    value: PyIntRef,
 }
 
-impl From<ArgIndex> for BigInt {
+impl From<ArgIndex> for PyIntRef {
     fn from(arg: ArgIndex) -> Self {
         arg.value
     }
 }
 
 impl Deref for ArgIndex {
-    type Target = BigInt;
+    type Target = PyIntRef;
 
     fn deref(&self) -> &Self::Target {
         &self.value
@@ -151,7 +150,7 @@ impl Deref for ArgIndex {
 impl TryFromObject for ArgIndex {
     fn try_from_object(vm: &VirtualMachine, obj: PyObjectRef) -> PyResult<Self> {
         Ok(Self {
-            value: obj.try_index(vm)?.as_bigint().clone(),
+            value: obj.try_index(vm)?,
         })
     }
 }