Function substring 

pub fn substring(string: &str, begin: i32, end: i32) -> String

Returns the substring between the given begin index and end index. The first character of string is at index 0

• begin –> inclusive
• end –> exclusive

Example:

 let input: &str = "Hello, World!";
 let result: String = funny_string::substring(input, 2, 6);
 // result now contains the string "llo,"