I\'m trying to append the last character of word to word but am having trouble implementing it. I added the `word += word[-1]` to do it but its not working. Any thoughts?\n```py\ndef gap(a,b):\n    return abs(ord(a)-ord(b))\n\ndef longestKInterspaceSubstring(word, k):\n    # Write your code here\n    temp,max="",""\n    for i in range(len(word)-1):\n        temp+=word[i]\n        if gap(word[i],word[i+1])>k:\n            max=max if len(max)>len(temp) else temp\n            temp=""\n        word += word[-1]\n    return max```

I\'m trying to append the last character of word to word but am having trouble implementing it. I added the word += word[-1] to do it but its not working. Any t