/// Returns true if the map contains any values for the specified key.
///
/// The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
/// form *must* match those for the key type.
Returns true if the map contains any values for the specified key.
The key may be any borrowed form of the map's key type, but `Hash` and `Eq` on the borrowed
form *must* match those for the key type.
Returns true if the map contains any values for the specified key . The key may be any borrowed form of the map ' s key type but ` Hash ` and ` Eq ` on the borrowed form * must * match those for the key type .
pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool
    where
        K: Borrow<Q>,
        Q: Hash + Eq,
    {
        self.enter().map_or(false, |x| x.contains_key(key))
    }
pub fn contains_key < Q : ? Sized > ( & self , key : & Q ) -> bool where K : Borrow < Q > , Q : Hash + Eq , { self . enter ( ) . map_or ( false , | x | x . contains_key ( key ) ) }
Returns true if the map contains any values for the specified key.
Returns true if the map contains any values for the specified key .
&self
key
&Q