C++.So I have to write a function that will trim off any punctuation from the beginning and end of the string.

For example:

...HeyThere... would become HeyThere

....Hey!!!!!There][][ would stay like Hey!!!!!There.

string cleanToken(string s) { // TODO: Write this function. }

I am required to do these things to the string:

1. Remove punctuation like above I mentioned

2. Return empty string if the string does not contain at least one letter.

3. Covert it to lowercase letters.