The only meaningful difference between the two is that the lambda is named <lambda> and the function is named even. I'm happy for you to use lambdas in an expr

The only meaningful difference between the two is that the lambda is named <lambda> and the function is named even. I'm happy for you to use lambdas in an expression context, if that's how you like to roll, but assignment is a statement anyway, so it doesn't matter there and you might as well choose the one that produces helpful tracebacks.