Message 408458 - Python tracker

According to the docs: https://docs.python.org/3/library/typing.html?#typing.TypedDict, there are two additional equivalent syntax for TypedDict definition.

Point2D = TypedDict('Point2D', x=int, y=int, label=str)
Point2D = TypedDict('Point2D', {'x': int, 'y': int, 'label': str})

However, the former one is quite confusing since we have the `total` keyword arg for TypedDict. In addition, PEP589(https://www.python.org/dev/peps/pep-0589/#id19) doesn't have this.

I think we could discard the definition syntax using keyword args in the doc.