int.format error handling

vm/src/builtins/int.rs

@@ -589,12 +589,9 @@ impl PyInt {
 
     #[pymethod(magic)]
     fn format(&self, spec: PyStrRef, vm: &VirtualMachine) -> PyResult<String> {
-        match FormatSpec::parse(spec.as_str())
+        FormatSpec::parse(spec.as_str())
             .and_then(|format_spec| format_spec.format_int(&self.value))
-        {
-            Ok(string) => Ok(string),
-            Err(err) => Err(vm.new_value_error(err.to_string())),
-        }
+            .map_err(|msg| vm.new_value_error(msg.to_owned()))
     }
 
     #[pymethod(magic)]