How to handle Optional values with lxml and mypy? #103
Description
A common error when running mypy on a project that uses lxml is that many of the lxml methods for retrieving information from XML trees return Optional values (i.e. a value that can be None or some other type such as _Element or str). This causes mypy to report many union-attr errors such as Item "None" of "Optional[_Element]" has no attribute "text".
The only "correct" solution that I'm aware of is to use type narrowing techniques such as assert value is not None or cast(_Element, value). This leads to a lot of verbose code for no real benefit, because in most cases I've tested the code enough to be confident that optional values will not be None at runtime, or I'm fine with a runtime AttributeError.
For those who use mypy with lxml, what's your solution for these errors? Is there a correct, non-verbose way to handle/silence them, or some way to tell mypy to ignore all union-attr errors that originate from lxml?