Rust is famous for its steep learning curve for a reason. Besides the borrow checker, lifetime, and many other concepts, functions and closures are among the most confusing concepts to grasp for Rust newcomers. Take a look:Example 1: Function and Closure Confusionprocess_data expects a function that takes an i32 and returns an i32. Both closures match this signature exactly. The first closure |x| x + 1 works perfectly, but the second closure |x| x * multiplier fails. What's the difference?Error:...