just wanted to draw peoples attention to below LOCs, which in notebooks will give you a graphical explanation of the objects involved.
##! pip install objgraph xdot
##! sudo apt-get install graphviz
import objgraph
##learn = language_model_learner(data_lm, bptt=70, drop_mult=0.3, pretrained_model=URLs.WT103) ## --> example
##objgraph.show_refs([learn])
Having that from @stas in this thread: IPyExperiments: Getting the most out of your GPU RAM in jupyter notebook
but thought these lines are of general value to just understand whats going on in notebooks 