How to count the number of occurrences of `None` in a list?

Just use sum checking if each object is not None which will be True or False so 1 or 0. lst = [‘hey’,’what’,0,False,None,14] print(sum(x is not None for x in lst)) Or using filter with python2: print(len(filter(lambda x: x is not None, lst))) # py3 -> tuple(filter(lambda x: x is not None, lst)) With python3 … Read more

Where is the NoneType located?

You can use type(None) to get the type object, but you want to use isinstance() here, not type() in {…}: assert isinstance(value, (str, type(None))) The NoneType object is not otherwise exposed anywhere in Python versions older than 3.10*. I’d not use type checking for that at all really, I’d use: assert value is None or … Read more