feature request: use { auto add closing bracket

use std::collections::HashMap;
                      ^---- if I add a '{' here it would be great if
                            you added a closing '}' before the semicolon. 

I can't personally think of a situation where I wouldn't want that.

Quite often we go from one import to two, and at that point we have to introduce the braces. You could even add a ', ' and put the carrot before the closing brace, but I think that might be a little disconcerting.

Also the corollary,

use std::collections::{HashMap};
                      ^ if this '{' is deleted then it would be great to auto remove the closing brace.