pub fn find_word_with_len(text: &str, len: usize) -> Option<String> {
let mut begin_idx = 0;
while begin_idx < text.chars().count() {
let word: String = text.chars().skip(begin_idx).take_while(|c| c.is_alphabetic()).collect();
let word_len = word.chars().count();
begin_idx += word_len;
let punct_len = text.chars().skip(begin_idx).take_while(|c| !c.is_alphabetic()).count();
begin_idx += punct_len;
if word_len <= len && word_len + punct_len >= len {
return Some(word.to_string());
}
}
None
}