A placeholder object for dictionary entries. The Dictionary class stores a three-way association: word string, part-of-speech property, and object. The object association is designed to allow the parser to come up with a list of objects that could match a given word, but the adv3L library doesn't use this feature. We instead figure out the word-to-object association by directly asking the objects in scope if they're associated with a word. We still need *something* to store as the object association for each word entry in the dictionary, though. That's where this object comes in: it's a dummy object that serves as the required object to associate with each word.

A language module can ignore this and use the word-object-property association feature of the dictionary, if desired.

dictionaryPlaceholder :   object