Highlighted of missing definitions

Jul 15 at 9:26 AM
I'm not sure whether this is supposed to be a feature or not, but if I have a function such as:
def test_function():
    f = open("test.txt")
    this_function_is_not_defined_anywhere(f)
Then Intellisense will show this_function_is_not_defined_anywhere as unknown but it won't be highlighted as missing in the editor.

Is it possible to highlight unknown objects? This would be very useful for typos if nothing else.