I'm struggling with learning vim regexps (I don't know any other regexp very well either), so the main problem is to define regexp that would match
some_function_call(simple_value, keyword=value)
keyword in this example.
So it should match a word if it's inside parens and have equal sign after it.
The next problem is how to define syntax files in vim. I would appreciate help with that, but It shouldn't be that hard to learn, so I can do that on my own probably.
EDIT based on the answer I've maid my own syntax script for python. Feel free to try it. enter link description here