resolve go-python#169 (comment)

Author: glaukiol1

os/os.module.go

@@ -266,14 +266,6 @@ func system(self py.Object, args py.Tuple) (py.Object, error) {
 	return py.Int(0), nil
 }
 
-// https://github.com/go-python/gpython/pull/169#discussion_r828767552 - type assertion
-func objectIsString(arg py.Object) bool {
-	if _, ok := arg.(py.String); ok {
-		return true
-	}
-	return false
-}
-
 func objectIsInt(arg py.Object) bool {
 	if _, ok := arg.(py.Int); ok {
 		return true