Whenever I go to to the line
bt.create_bayesian_tear_sheet(live_start_date='2014-1-1')
in tear sheets and press return, I get an error message:
NameError Traceback (most recent call last)
in ()
----> 1 bt.create_returns_tear_sheet(live_start_date='2014-1-1')
NameError: name 'bt' is not defined
Why?