Given an "in" string length 4, such as "<<>>", and a word, return a new string where the "in" String is in the middle of the word, e.g. "wo<<>>rd". We'll say that length()/2 is the middle of the word whether or not the length is even. Note: use str.substring(i, j) to extract the String starting at index i and going up to but not including index j.