That's because your type is Optional[TypeOfVar] though; if you try using that variable in a place that expects just TypeOfVar before it's set, you should get an error.
Let me restate. To prevent ugliness in typing, either
* Python should have a way of declaring variables without setting them to None, so we can type hint them to their actual types. Pre-declaration is very important for a prototyping language, and needs to be done in a way that the variable is visible to dir().
* Come up with a cleaner syntax than the wordy Optional[]. Thankfully, they have recently moved on from the ugly Union[a,b] to the more readable a | b. Something more readable could be done for Optional.
A very common pattern in python is to declare all instance variables of a class in the __init__ method by setting them to None. This is done for
* code readability; all relevant variables are in one place
* Python is a prototyping language, and a very common usage pattern is doing dir(object) to determine the names of all variables that could be set to something.
