public boolean lookup(long x) {

    /* Must check that x is not blank because otherwise you could
     * get a false positive if the blank value was a value you
     * were legitimately testing to see if it was in the set.
     */
    return x != blank && (t1[h1(x)] == x || t2[h2(x)] == x);
  }
Return true if and only if the value x is present in the set.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/CuckooSetLong.java