The function appears to be a Caesar cipher shifting the input 17 positions forward for both upper and lowercase letters and leaving digits and other characters unchanged.

[CODE]: 
```python
def Caesar_shift(input_string: str) -> str:
    output = ""
    for char in input_string:
        if char.isalpha():
            shift = 17
            if char.islower():
                output += chr(((ord(char) - ord('a') + shift) % 26) + ord('a'))
            else: # char.isupper()
                output += chr(((ord(char) - ord('A') + shift) % 26) + ord('A'))
        else: # not an alphabet character
            output += char
    return output
```