If a have the string `calculation = '1+1x8'`. How can I convert this into `calculation = 1+1*8`? I tried doing something like

```
for char in calculation:
    if char == 'x':
        calculation = calculation.replace('x', *)

    # and

    if char == '1':
        calculation = calculation.replace('1', 1)

```

This clearly doesn't work, since you can't replace just one character with an integer. The entire string needs to be an integer, and if I do that it doesn't work either since I can't convert `'x'` and `'+'` to integers