Control flow is a fundamental concept in programming that allows you to dictate how your code executes based on certain conditions. In Rust, one of the ways to control the flow of your program is by using if-else statements.

In this challenge, you will implement a function that checks whether a number is positive, negative, or zero. Depending on the value, your function should return a corresponding string message.

Your task is to complete the function check_number_sign that takes an integer i32 as input and returns a String indicating whether the number is "positive", "negative", or "zero".

• If the number is greater than zero, return "positive".
• If the number is less than zero, return "negative".
• If the number is equal to zero, return "zero".

let result = check_number_sign(10);
assert_eq!(result, "positive");
 
let result = check_number_sign(-5);
assert_eq!(result, "negative");
 
let result = check_number_sign(0);
assert_eq!(result, "zero");

• You can use the if, else-if, and else keywords to implement the control flow.
• Remember to return the result as a String.