The goal of this exercise is to convert a string to a new string where each character in the new string is `"("` if that character appears only once in the original string, or `")"` if that character appears more than once in the original string. Ignore capitalization when determining if a character is a duplicate.

## Examples
```
"din"      =>  "((("
"recede"   =>  "()()()"
"Success"  =>  ")())())"
"(( @"     =>  "))((" 
```

**Notes**

Assertion messages may be unclear about what they display in some languages. If you read `"...It Should encode XXX"`, the `"XXX"` is the expected result, not the input!