Object to hold dict of tags as keys, and the list of times as items
make a list of all unique items and how many times that item shows up in the journal
return a list of tuples: [ (freq, item), ... ]
return a list of the keys... most frequent first
look at only one association
will not fail if key does not exist.
return a list of keys that have that item
remove all instances of item from all associations
Enter search terms or a module, class or function name.