public Holder(){
        queryVector = new Vector<>();
        FREE_DOC_ID = 0;
        B1 = 1;
        B2 = 1;
        index = new HashMap<>();
        tf_Idf = new HashMap<>();
        docVec = new HashMap<>();
        vecLenght = new HashMap<>();
        cosineSimilarities = new HashMap<>();
        docIdList = new ArrayList<>();
        leaders = new ArrayList<>(); 
        followers = new HashMap<>();
    
    }