def test_example_1(self):
   self.assertEqual(lexico_sort(["acb", "abc", "bca"], "abc"),
                    ["abc","acb","bca"])
 def test_empty(self):
   self.assertEqual(lexico_sort([], ""),
                    [])
 def test_large(self):
   a_lot = 10000000
   self.assertEqual(lexico_sort(["a" * a_lot, "b" * a_lot], "ba"),
                    ["b" * a_lot, "a" * a_lot])
 def test_example_3(self):
   self.assertEqual(lexico_sort(["aaa","aa",""], "a"),
                    ["", "aa", "aaa"])