5.4.2 Predicates for managing dicts
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Availability:built-in
put_dict(+Key, +DictIn, +Value, -DictOut)
DictOut is a new dict created by replacing or adding Key-Value to DictIn. For example: 
?- A = point{x:1, y:2}.put(x, 3).
A = point{x:3, y:2}.

This predicate can also be accessed by using the functional notation, in which case Key can also be a *path* of keys. For example: 

?- Dict = _{}.put(a/b, c).
Dict = _6096{a:_6200{b:c}}.