How can I compare integers in python the same way CompareTo() in C# does?

As far as I know, in .NET Framework there is a method Int32.CompareTo(), which returns 0 if the numbers are equal, -1 if the number in the parenthesis is higher, otherwise 1. Is there an existing method for this, in python with the same return values, or do I have to write one myself?

Maybe in some third-party library, but no, in "vanilla" Python 3.x there is no method to do that, though code to achieve something similar should be as simple as this:

def compare_to(val1: int, val2: int) -> int:
    if val1 > val2:
        return 1
    elif val1 < val2:
        return -1
    elif val1 == val2:
        return 0

Or, for something closer to what you described using a custom subclass of int:

class Int32(int):
    def compare_to(self, value: int):
        if self > value:
            return 1
        elif self < value:
            return -1
        elif self == value:
            return 0