Create a function `isAlt()` that accepts a string as an argument and validates whether the vowels (a, e, i, o, u) and consonants are in alternate order.
```python
is_alt("amazon")
// true
is_alt("apple")
// false
is_alt("banana")
// true
```
Arguments consist of only lowercase letters.
def is_alt(s):
    return helper(s, 0, 1) if s[0] in "aeiou" else helper(s, 1, 0)
def helper(s, n, m):
    for i in range(n, len(s), 2):
        if s[i] not in "aeiou":
            return False
    for i in range(m, len(s), 2):
        if s[i] in "aeiou":
            return False
    return True
def is_alt(s):
    return helper(s, 0, 1) if s[0] in "aeiou" else helper(s, 1, 0)
def helper(s, n, m):
    for i in range(n, len(s), 2):
        if s[i] not in "aeiou":
            return False
    for i in range(m, len(s), 2):
        if s[i] in "aeiou":
            return False
    return True