-import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
-import com.google.common.collect.ImmutableRangeSet;
-import com.google.common.collect.Range;
-import com.google.common.collect.RangeSet;
-import com.google.common.collect.TreeRangeSet;
-import java.util.Collection;
-import java.util.Objects;