code: package edu.jhu.thrax.hadoop.features.pivot;
  
  import java.util.Set;
  
  import org.apache.hadoop.io.Writable;
  
  import edu.jhu.thrax.hadoop.datatypes.FeatureMap;
  import edu.jhu.thrax.hadoop.features.Feature;
  
  public interface PivotedFeature extends Feature {
  
  	public Set<String> getPrerequisites();
  
  	public Writable pivot(FeatureMap src, FeatureMap tgt);
  
  	public void initializeAggregation();
  	
  	public void aggregate(FeatureMap a);
  
  	public Writable finalizeAggregation();
  	
  	public Set<String> getLowerBoundLabels();
  	
  	public Set<String> getUpperBoundLabels();
  }
  