fn contains(&self, key: K) -> bool {
        match self.get(key) {
            Some(_) => true,
            None => false,
        }
    }
/// Returns true if this container contains the key.
Returns true if this container contains the key.
Returns true if this container contains the key .
fn contains(&self, key: K) -> bool {
        match self.get(key) {
            Some(_) => true,
            None => false,
        }
    }
fn contains ( & self , key : K ) -> bool { match self . get ( key ) { Some ( _ ) => true , None => false , } }
Returns true if this container contains the key.
Returns true if this container contains the key .
&self
key
K