public interface KnownSizeEstimation
SizeEstimator more accurate size estimation.
 When a class extends it, SizeEstimator will query the estimatedSize first.
 If estimatedSize does not return None, SizeEstimator will use the returned size
 as the size of the object. Otherwise, SizeEstimator will do the estimation work.
 The difference between a KnownSizeEstimation and
 SizeTracker is that, a
 SizeTracker still uses SizeEstimator to
 estimate the size. However, a KnownSizeEstimation can provide a better estimation without
 using SizeEstimator.| Modifier and Type | Method and Description | 
|---|---|
long | 
estimatedSize()  |