str (first argument) for num times (second argument). Return an empty string if num is not a positive number.
Remember to use Read-Search-Ask if you get stuck. Write your own code.
repeatStringNumTimes("*", 3) should return "***".
    testString: assert(repeatStringNumTimes("*", 3) === "***", 'repeatStringNumTimes("*", 3) should return "***".');
  - text: repeatStringNumTimes("abc", 3) should return "abcabcabc".
    testString: assert(repeatStringNumTimes("abc", 3) === "abcabcabc", 'repeatStringNumTimes("abc", 3) should return "abcabcabc".');
  - text: repeatStringNumTimes("abc", 4) should return "abcabcabcabc".
    testString: assert(repeatStringNumTimes("abc", 4) === "abcabcabcabc", 'repeatStringNumTimes("abc", 4) should return "abcabcabcabc".');
  - text: repeatStringNumTimes("abc", 1) should return "abc".
    testString: assert(repeatStringNumTimes("abc", 1) === "abc", 'repeatStringNumTimes("abc", 1) should return "abc".');
  - text: repeatStringNumTimes("*", 8) should return "********".
    testString: assert(repeatStringNumTimes("*", 8) === "********", 'repeatStringNumTimes("*", 8) should return "********".');
  - text: repeatStringNumTimes("abc", -2) should return "".
    testString: assert(repeatStringNumTimes("abc", -2) === "", 'repeatStringNumTimes("abc", -2) should return "".');
  - text: The built-in repeat()-method should not be used
    testString: assert(!/\.repeat/g.test(code), 'The built-in repeat()-method should not be used');
```