def readfile(filename):
'''
read file
return format :
[ ['EU', 'B-ORG'], ['rejects', 'O'], ['German', 'B-MISC'], ['call', 'O'], ['to', 'O'], ['boycott', 'O'], ['British', 'B-MISC'], ['lamb', 'O'], ['.', 'O'] ]
'''
f = open(filename,encoding='utf-8')
sentences = []
sentence = []
for line in f:
#print(line)
if len(line)==0 or line[0]=="\n":
if len(sentence) > 0:
sentences.append(sentence)
#print(sentence)
sentence = []
continue
splits = line.split(' ')
sentence.append([splits[0],splits[-1]])
#print([splits[0],splits[-1]])
if len(sentence) >0:
sentences.append(sentence)
sentence = []
return sentences
