@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		WordCoWritable other = (WordCoWritable) obj;
		if (first == null) {
			if (other.first != null)
				return false;
		} else if (!first.equals(other.first))
			return false;
		if (second == null) {
			if (other.second != null)
				return false;
		} else if (!second.equals(other.second))
			return false;
		return true;
	}