Here is an example function in Python that checks if a string is a palindrome:

```
def is_palindrome(s):
    # Reverse the string
    rev = s[::-1]
    # If the reversed string is the same as the original, return True
    if s == rev:
        return True
    # Otherwise, return False
    else:
        return False
```

The function takes in a string `s` as input and reverses it using the slice notation `[::-1]`. It then checks if the reversed string is equal to the original string and returns `True` if it is, and `False` otherwise.

You can call this function with a string like this:

```
s = "racecar"
print(is_palindrome(s)) # Output: True
```
Scrivete una funzione che verifichi se una stringa è palindromo.