package iitb.CRF;/** * A single feature returned by the FeatureGenerator needs to support this interface. * @author Sunita Sarawagi * */ public interface Feature {    int index(); /** the index of this feature from 0..numFeatures-1. */    int y();  /** has to be a label index from 0..numLabels-1 */    int yprev(); /** can be -1 if the feature is a state, rather than an edge feature */    float value(); /** any real value, don't return anything if 0 for efficiency */    int[] yprevArray(); /** for history of length greater than 1, return array of prev values, will be ignore of history of length 1*/  };