I am a dictionary holding only weakly on my keys. This is a bit dangerous since at any time my keys can go away. Clients are responsible to register my instances by WeakArray such that the appropriate actions can be taken upon loss of any keys.

See WeakRegistry for an example of use.

	adding
	add:

	finalization
	finalizeValues finalizeValues:

	private
	fixCollisionsFrom: rehash scanFor: scanForNil:

	accessing	top
	at:put: Set the value at key to be anObject. If key is not found, create a new entry for key and set is value to anObject. Answer anObject.
	keysDo: Evaluate aBlock for each of the receiver's keys.

	adding	top
	add: Include newObject as one of the receiver's elements, but only if not already present. Answer newObject.

	finalization	top
	finalizeValues remove all nil keys and rehash the receiver afterwards
	finalizeValues: Remove all associations with key == nil and value is in finiObjects. This method is folded with #rehash for efficiency.

	private	top
	fixCollisionsFrom: The element at index has been removed and replaced by nil.
	rehash Rehash the receiver. Reimplemented to allow for multiple nil keys
	scanFor: ar 10/21/2000: The method has been copied to this location to indicate that whenever #scanFor: changes #scanForNil: must be changed in the receiver as well.
	scanForNil: Private. Scan the key array for the first slot containing nil (indicating an empty slot). Answer the index of that slot.