More like camelcase is not convention in Python. If this person added defensive programming concepts with "#--end function" and are using camelcase, I'd say Python isn't their regular language.

Love this one! Didn't know there was a counter from collections that could do that. It essentially provides an iterable hashtable, right?

Great solution! Don't think the strip() is necessary, and fstrings a more gracious way for prepending the hashtag at the beginning of the string. Also, as someone else mentioned below, it'd have to check if the resulting string s is of size len(s) < 140 instead of len(s) < = 140 since the description states that the final (aka with hashtag) string is of length smaller or equal to 140 characters.

Because adding an additional variable to store the final result in would require an additional line.