set_universe functions are finally being removed from the Quantopian API. These functions have been deprecated since we updated to Quantopian 2 in April 2016.
You can still select a dynamic trading universe based on dollar volume in pipeline. Better yet, you can use the Q1500US to trade the top 1500 most liquid stocks. The attached backtest defines a pipeline that selects the top 10% of stocks in the Q1500US by dollar volume.
We expect the removal of these functions to take place soon so you should consider updating your algorithms if they still use
If you have any questions, or need help updating your code, please let us know.