About 5 years ago I was given this cactus, in a minuscule pot and severely dehydrated. To my surprise it responded to watering and repotting really well. About 18 months ago I woke one morning to find it leaned over 90 degrees, bent at the base, the top having become too heavy for the base to support. I built a Zimmer frame for it ;) and left it to it. It's now getting a bit on the tall side for its location and I don't really have anywhere else to put it. Is there a way to encourage it to grow shoots/put some energy into sideways expansion or is it the sort that only grows upwards in a single stick?