Possibility to collapsed threads with persistance

The user have the possibility to collapse threads of emails. 
The information about the collapsed threads are kept inside the user settings under the module Mail saved by the key : threadsCollapsed
Would be better to do:

if ((mailboxThreadsCollapsed = [threadsCollapsed objectForKey:keyForMsgUIDs])) ..

and avoid:

          mailboxThreadsCollapsed = [threadsCollapsed objectForKey:keyForMsgUIDs];

after.

Same thing below in markMessageUncollapseAction