parentheses in default argument values breaks syntax highlighting

[jordanbtucker]

When parentheses are used in the expression for the value of a default argument of a function, it breaks highlighting for its function's argument list. It's easier to understand with an example:

func = (arg1, arg2 = 'item(s)') ->

Here's how it looks:

Here are some similar examples of how it should look:

Here are some other examples of it being broken: