There is no one standard that fits all cases e.g., I've written useful code in Groovy/Java but I wouldn't dream of claiming I know the languages (or want to know), on the other hand I have a lot of experience with Python code but I see there is much to be learned (the more you know, the more there is to learn).

You can learn something useful in a few ours. It is arrogant to claim you know everything even after decades of experience.