dave on Nostr: fn common_char_functional<'a>(str1: &'a str, str2: &'a str) -> &'a str { let result = ...

fn common_char_functional<'a>(str1: &'a str, str2: &'a str) -> &'a str {
let result = str1.chars()
.filter(|ch1| str2.contains(*ch1))
.collect::<String>();
Box::leak(result.into_boxed_str())
}