The asymmetry is apparent if the code gets refactored to continuation/callback style or mutation of a more complex data structure, the first method will fall th

The asymmetry is apparent if the code gets refactored to continuation/callback style or mutation of a more complex data structure, the first method will fall through and execute the second instruction set. Return is a special operator in this sense in that it breaks control flow and the ordinary control flow of the first method is not capturing the exhaustiveness of the two cases. In idiomatic rust, return isn't used except for exceptional cases that break the control flow of the method and the second example is more commonly seen without return statements at all. Idiomatic python also typically early exits in the beginning with a return on invalid parameters or state with a tail position return being the usual actual return value. Because of these conventional practices, breaking the exhaustive if-else control structure makes the indented return appear exceptional (like an invalidity). If you follow these conventions than naturally the return statement begins to appear redundant except in the break-control-flow cases and the choice of the rust convention begins to make sense: in all languages return is a statement equivalent to break.