# Functions
MakeChecker initializes a new Checker.
# Constants
Data indicates that at least a key or range in the level overlaps with the key range of interest.
None indicates that the key range of interest doesn't overlap any tables on the level.
OnlyBoundary indicates that there is boundary overlap but no data overlap.
# Interfaces
IteratorFactory is an interface that is used by the Checker to create iterators for a given table.