this.definitelyNullSet.and(other.definitelyNullSet);
this.contents.and(other.contents);
	public void mergeWith(DefinitelyNullSet other) {		if (this.isBottom() || other.isTop()) {			return;		}				if (this.isTop() || other.isBottom()) {			this.makeSameAs(other);			return;		}				// Result is intersection of sets		this.definitelyNullSet.and(other.definitelyNullSet);	}