Your job is to figure out the index of which vowel is missing from a given string:
* `A` has an index of 0,
* `E` has an index of 1, 
* `I` has an index of 2, 
* `O` has an index of 3,
* `U` has an index of 4.
**Notes:** There is no need for string validation and every sentence given will contain all vowles but one. Also, you won't need to worry about capitals.
## Examples
```
"John Doe hs seven red pples under his bsket"          =>  0  ; missing: "a"
"Bb Smith sent us six neatly arranged range bicycles"  =>  3  ; missing: "o"
```
def absent_vowel(x): 
    VOWELS = set('aeiou')
    INDEX = {
        'a': 0,
        'e': 1,
        'i': 2,
        'o': 3,
        'u': 4,
    }
    missing = VOWELS.difference(set(x.lower()))
    return INDEX.get(''.join(missing))
def absent_vowel(x): 
    VOWELS = set('aeiou')
    INDEX = {
        'a': 0,
        'e': 1,
        'i': 2,
        'o': 3,
        'u': 4,
    }
    missing = VOWELS.difference(set(x.lower()))
    return INDEX.get(''.join(missing))