Function sdb::btree::del::del

pub fn del<T, K, V, P>(
    txn: &mut T, 
    db: &mut Db_<K, V, P>, 
    key: &K, 
    value: Option<&V>
) -> Result<bool, <T as LoadPage>::Error> where
    K: Storable + Debug + PartialEq<K> + ?Sized,
    V: Storable + Debug + PartialEq<V> + ?Sized,
    T: AllocPage + LoadPage + Debug,
    P: BTreeMutPage<K, V> + Debug, 

If value is None, delete the first entry for key from the database, if present. Else, delete the entry for (key, value), if present.