---
id: 5d79253358e8f646cbeb2bb0
title: Part 15
challengeType: 0
---
# --description--
Change the `"+"` in the call to `infixToFunction` to `fn`.
`fn` is the operator that the user inputs (`+`, `-`, `*` or `/`) - we use `infixToFunction` to get the function that corresponds to it.
# --hints--
See description above for instructions.
```js
assert(
code
.replace(/\s/g, '')
.includes('str.replace(regex,(match,arg1,fn,arg2)=>infixToFunction[fn])')
);
```
# --seed--
## --before-user-code--
```html
Spreadsheet
```
## --after-user-code--
```html
```
## --seed-contents--
```html
```
# --solutions--
```html
```