function showMagicians(magicians: string[]): void {
    magicians.forEach(magician => console.log(magician));
}

function makeGreat(magicians: string[]): void {
    
    for (let i = 0; i < magicians.length; i++) {
        magicians[i] = "the Great " + magicians[i];
    }
}
let magicians: string[] = ['Harry Houdini', 'David Copperfield', 'Penn & Teller'];
console.log("Original list of magicians:");
showMagicians(magicians);
makeGreat(magicians);
console.log("\nModified list of magicians:");
showMagicians(magicians);