Create a recursive function that takes two parameters and repeats the string n number of times. The first parameter txt is the string to be repeated and the second parameter is the number of times the string is to be repeated.
repetition("ab", 3) ➞ "ababab"
repetition("kiwi", 1) ➞ "kiwi"
repetition("cherry", 2) ➞ "cherrycherry"
The second parameter of the function is positive integer.