python - skip-thought Theano model - list not declared -

i have defined list x take contents of file , feed preprocessor of skip-though model in theano. error says x not defined.

https://github.com/ryankiros/skip-thoughts/blob/master/skipthoughts.py

def encode(model, x, use_norm=true, verbose=true, batch_size=128, use_eos=false):     """     encode sentences in list x. each entry return vector     """     # first, preprocessing     x = preprocess(x)      # word dictionary , init     d = defaultdict(lambda : 0)     w in model['utable'].keys():         d[w] = 1     ufeatures = numpy.zeros((len(x), model['uoptions']['dim']), dtype='float32')     bfeatures = numpy.zeros((len(x), 2 * model['boptions']['dim']), dtype='float32')      # length dictionary     ds = defaultdict(list)     captions = [s.split() s in x]     i,s in enumerate(captions):         ds[len(s)].append(i)   def preprocess(text):     """     preprocess text encoder     """     x = []  #for _chat.txt list_______________________________________     f= open("/var/www/html/_chat.txt", "r")     file_list = f.readlines()     first_three = file_list[1:3]     x = [x.replace('\t',' ') x in first_three]     x = [x.replace('\x00','') x in x]     x = [x.replace(' \r\n','') x in x] #______________________________________________________________      sent_detector = nltk.data.load('tokenizers/punkt/english.pickle')     t in text:         sents = sent_detector.tokenize(t)         result = ''         s in sents:             tokens = word_tokenize(s)             result += ' ' + ' '.join(tokens)         x.append(result)     return x