Explain the use of Go's closures for encapsulating variables in functions?

In Go, a closure is a function that captures and "encloses" the values of its surrounding environment, allowing them to be accessed and manipulated even after the outer function has returned. This is achieved by defining the function within the context of the surrounding environment, so that it has access to its variables.

Closures are useful for encapsulating and abstracting code, allowing for more modular and reusable code. They are commonly used to create functions with specific behaviors that can be passed around as values.

For example, consider the following code:

func adder(x int) func(int) int {
    return func(y int) int {
        return x + y
    }
}

func main() {
    addFive := adder(5)
    result := addFive(3) // result is 8
}

In this example, **adder** is a function that returns a closure that adds its argument to the argument passed to **adder**. When **adder(5)** is called, it returns a new function that adds 5 to its argument. This returned function is then assigned to **addFive**, which can be called with an argument to add 5 to it.

Closures are powerful because they allow us to create functions that remember state between calls. This can be useful for creating iterators, event listeners, or any other type of function that needs to maintain some state.