map.rs

impl<K,U,V> Map<K,U,V>
    where K: Serialize + DeserializeOwned + Ord + Clone,
          U: Serialize + DeserializeOwned + Ord + Clone,
          V: Serialize + DeserializeOwned + Clone,
{
    pub fn new(db: Arc<DB>, cf: ColumnFamily) -> Map<K,U,V> {
        Map { db, cf, p1: PhantomData, p2: PhantomData, p3: PhantomData }
    }

    pub fn create<'a, I>(&self, key: &K, values: I, ttl: Option<i64>) -> Result<(), Error>
        where I: Iterator<Item=(U,V)>
    {
        let kbuf = serialize(&key, Infinite)?;
        let mut vbuf : Vec<u8> = Vec::with_capacity(32);
        set_ttl(&mut vbuf, ttl)?;
        let val : BTreeMap<U,V> = values.collect();
        serialize_into(&mut vbuf, &val, Infinite).map_err(Error::from)?;
        self.db.put_cf(self.cf, kbuf.as_slice(), vbuf.as_slice()).map_err(
            Error::from,
        )
    }
}

... 

let tbl = db.get_map::<String, String, String>("latin").unwrap();
let entries2 : Vec<(String, String)> = keys2.into_iter().zip(vals2.into_iter()).collect();

tbl.create(&key1, entries1.iter(), None).unwrap();


///
error[E0271]: type mismatch resolving `<std::slice::Iter<'_, (std::string::String, std::string::String)> as std::iter::Iterator>::Item == (std::string::String, std::string::String)`
   --> src/lib.rs:573:13
    |
573 |         tbl.create(&key1, entries1.iter(), None).unwrap();
    |             ^^^^^^ expected reference, found tuple
    |
    = note: expected type `&(std::string::String, std::string::String)`
               found type `(std::string::String, std::string::String)`