import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * An accumulator that selects the "top" {@code k} elements added to it, relative to a provided
 * comparator. "Top" can mean the greatest or the lowest elements, specified in the factory used to
 * create the {@code TopKSelector} instance.
 *