fn eq(&self, other: &BTreeMap<K, V>) -> bool {
        self.len() == other.len() && self.iter().zip(other).all(|(a, b)| a == b)
    }
Gets a mutable iterator over the entries of the map, sorted by key.

# Examples

Basic usage:

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

let mut map = BTreeMap::new();
map.insert("a", 1);
map.insert("b", 2);
map.insert("c", 3);

// add 10 to the value if the key isn't "a"
for (key, value) in map.iter_mut() {
if key != &"a" {
*value += 1
benchmarks/haystacks/code/rust-library.rs