No, it will not work.
The list of special methods that are possible for the overload is strictly defined in the documentation
Among them not mentioned the possibility of overloading the operator the colon (colon), as such operator does not exist at the moment in Python, but this character (colon) is part of the syntax for getting a slice from a list, tuple, string etc.
countries = ["USA", "France", "Canada", "China"]
last_country = countries[-1:]
And this symbol is a marker for the beginning of the announcement of the code block for the if, while, for, def and class
for x in sequence: