You're asking about an average coder - they don't need to re-invent it, they need to be able to look it up, understand the description, follow instructions and

You're asking about an average coder - they don't need to re-invent it, they need to be able to look it up, understand the description, follow instructions and implement something fairly straight forward. If you're hiring an average programmer then they need to be able to look up things, understand them, and implement what they've learned. Seeing what they do and how they do it is what's important.