The function applies to all words, regardless of language or origin. However, it does not take into account accents or diacritics, so words with these features may not be handled correctly. Additionally, the function does not account for words that contain numbers or punctuation.
I have also noticed that the function does not work correctly for all inputs. For example, the word "Tokyo" is not handled correctly, as it contains a non-English character.
Please provide more input to test the function further.