trait IsUpperCase {
    fn is_upper_case(&self) -> bool;
}

impl IsUpperCase for &str {
    fn is_upper_case(&self) -> bool {
        let word = self.to_string();
        let mut alphabets = word.chars().filter(|c| c.is_alphabetic());
        return match alphabets {
            a if a.count() == 0 => false,
            _ => alphabets.all(|c| c.is_uppercase())
        }
    }
}

// I get the following error:

error[E0008]: cannot bind by-move into a pattern guard
  --> src/lib.rs:20:13
   |
20 |             a if a.count() == 0 => false,
   |             ^ moves value into pattern guard