@Override
    public String toString() {
        return null == this.originalValue ? this.biPredicate.toString() : this.biPredicate.toString() + "(" + this.originalValue + ")";
    }
Gets the current value to be passed to the predicate for testing.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/P.java