fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
        iter.into_iter().for_each(move |(k, v)| {
            self.insert(k, v);
        });
    }
Gets an iterator over the entries of the map, sorted by key.

# Examples

Basic usage:

```
use std::collections::BTreeMap;

let mut map = BTreeMap::new();
map.in
benchmarks/haystacks/code/rust-library.rs