In this Kata, we will check if a string contains consecutive letters as they appear in the English alphabet and if each letter occurs only once. 
```Haskell
Rules are: (1) the letters are adjacent in the English alphabet, and (2) each letter occurs only once.
For example: 
solve("abc") = True, because it contains a,b,c
solve("abd") = False, because a, b, d are not consecutive/adjacent in the alphabet, and c is missing.
solve("dabc") = True, because it contains a, b, c, d
solve("abbc") = False, because b does not occur once.
solve("v") = True
```
All inputs will be lowercase letters. 
More examples in test cases. Good luck!
def solve(s):
    return len(s) == ord(max(s)) - ord(min(s)) + 1
def solve(s):
    return len(s) == ord(max(s)) - ord(min(s)) + 1