How do you grow spiral bamboo?

I recently purchased a lucky bamboo plant from a farmers market that came in the shape of a upwards spiral, just like this: http://www.plant-care.com/images/lucky-b...

I was wondering how to keep growing it like that instead of having it grow into straight line from that point on. Anyone know?

How do you grow spiral bamboo?
When the plant grows, it grows in the direction of sunlight. So when the plant is growing, the grower turns the pot the bamboo grows in say, 45o each day or something, having the bamboo grow around something too.
Reply:To make the bamboo spiral, they pull it out of the water for a while and the bamboo softens. It is wrapped around a tube and put back into the water, where it re hardens in the spiral around the tube.