stanford nlp – how to lower case all word in brwon corpus

Xdocwords = ()
Y = ()


for category in brown.categories():
  
  for fileid in brown.fileids(category):
     for word in brown.words(categories=category):
      word = word.lower()
      Xdocwords.append(word)
  Xdocwords.append(brown.words(fileid))
      
  Y.append(category)
print(Y(8))
print(Xdocwords(100)(0:50))

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i am trying to lower all word and thn to disply the list and categry. but i get the out wth one word onky what i am doing wrong i have use freqdis method but doesnt work