aaa=[[('s1',)], [('s1',)], [('s1',)], [('s1', 's2')], [('s1', 's2')], [('s1', 's2')], [('s1', 's2')]]
bbb=[]
for each in aaa: for ec in each: bbb.append(list(ec))
[list(i[0]) for i in aaa]
