In this Kata, you will write a function `doubles` that will remove double string characters that are adjacent to each other.
For example:
`doubles('abbcccdddda') = 'aca'`, because, from left to right:
```Haskell
a) There is only one 'a' on the left hand side, so it stays.
b) The 2 b's disappear because we are removing double characters that are adjacent. 
c) Of the 3 c's, we remove two. We are only removing doubles. 
d) The 4 d's all disappear, because we first remove the first double, and again we remove the second double.
e) There is only one 'a' at the end, so it stays.
```
Two more examples: `doubles('abbbzz') = 'ab'` and `doubles('abba') = ""`. In the second example, when we remove the b's in `'abba'`, the double `a` that results is then removed.
The strings will contain lowercase letters only. More examples in the test cases. 
Good luck!
import re
def doubles(s):
    while len(re.sub(r'([a-z])\1',"",s)) != len(s):
        s = re.sub(r'([a-z])\1',"",s)
    return s
import re
def doubles(s):
    while len(re.sub(r'([a-z])\1',"",s)) != len(s):
        s = re.sub(r'([a-z])\1',"",s)
    return s