Create a function that accepts a string of space separated numbers and returns the highest and lowest number (as a string).
HighLow("1 2 3 4 5") ➞ "5 1" HighLow("1 2 -3 4 5") ➞ "5 -3" HighLow("1 9 3 4 -5") ➞ "9 -5" HighLow("13") ➞ "13 13"