using DefineVariable function in nested logit

Question

I want to write a nested logit estimation program. in writing the following code: TRAIN_TT_SCALED = DefineVariable('TRAIN_TT_SCALED', TRAIN_TT / 100.0) I got this error:

NameError Traceback (most recent call last) Cell In[6], line 1 ----> 1 TRAIN_TT_SCALED = DefineVariable('TRAIN_TT_SCALED', swissmetro_wide.TRAIN_TT / 100.0)

NameError: name 'DefineVariable' is not defined

from which module I should find DefineVariable?

I expect to get the variable that I can multiply to a Beta variable.