Constant CHARS_NO_SPECIAL 

pub const CHARS_NO_SPECIAL: &str = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZZYXWVUTSRQPONMLKJIHGFEDCBA9876543210zyxwvutsrqponmlkjihgfedcba";