/// Returns `true` if the list contains a value for the specified key.
///
/// The key may be any borrowed form of the list's key type, but the
/// ordering on the borrowed form *must* match the ordering on the key type.
///
/// # Examples
///
/// ```
/// use arena_collections::AssocList;
///
/// let entries = [(1, "a")];
/// let alist = AssocList::new(&entries[..]);
/// assert_eq!(alist.contains_key(&1), true);
/// assert_eq!(alist.contains_key(&2), false);
/// ```
Returns `true` if the list contains a value for the specified key.
The key may be any borrowed form of the list's key type, but the
ordering on the borrowed form *must* match the ordering on the key type.
Returns ` true ` if the list contains a value for the specified key . The key may be any borrowed form of the list ' s key type but the ordering on the borrowed form * must * match the ordering on the key type .
pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool
    where
        K: Borrow<Q>,
        Q: PartialEq,
    {
        get_last_entry(&self.entries, key).is_some()
    }
pub fn contains_key < Q : ? Sized > ( & self , key : & Q ) -> bool where K : Borrow < Q > , Q : PartialEq , { get_last_entry ( & self . entries , key ) . is_some ( ) }
Returns `true` if the list contains a value for the specified key.
Returns ` true ` if the list contains a value for the specified key .
&self
key
&Q
examples
```
use arena_collections::AssocList.

let entries = [(1, "a")];
let alist = AssocList::new(&entries[..]);
assert_eq!(alist.contains_key(&1), true);
assert_eq!(alist.contains_key(&2), false);
```
` ` ` use arena_collections :: AssocList . let entries = [ ( 1 " a " ) ] ; let alist = AssocList :: new ( &entries [ .. ] ) ; assert_eq! ( alist . contains_key ( &1 ) true ) ; assert_eq! ( alist . contains_key ( &2 ) false ) ; ` ` `