putAll

    pub fn putAll(m: *Map, other: *const Map) Allocator.Error!void {
        const gpa = m.allocator;
        try m.array_hash_map.ensureUnusedCapacity(gpa, other.array_hash_map.count());
        const start = m.count();
        errdefer while (m.array_hash_map.count() > start) {
            const kv = m.array_hash_map.pop().?;
            gpa.free(kv.key);
            gpa.free(kv.value);
        };
        for (other.array_hash_map.keys(), other.array_hash_map.values()) |key, value| {
            try m.put(key, value);
        }
    }