AttributeError: 'list' object has no attribute 'lower'

[Token Type]

> structures are simple, just plain print will work, but for more 
> 
> complicated structures, pprint.pprint() is a life saver.
> 

I did try . However, 

>>> pprint.pprint(lemma_list)

Traceback (most recent call last):
  File "<pyshell#74>", line 1, in <module>
    pprint.pprint(lemma_list)
NameError: name 'pprint' is not defined
>>> pprint.pprint(synset_list)

Traceback (most recent call last):
  File "<pyshell#75>", line 1, in <module>
    pprint.pprint(synset_list)
NameError: name 'pprint' is not defined
>>>