Question: 
Write a function to extract elements that occur singly in the given tuple list.


Model's Code:
def extract_singly(tuple_list):
    from collections import Counter
    flattened = [item for sublist in tuple_list for item in sublist]
    counts = Counter(flattened)
    return [item for item in counts if counts[item] == 1] + [item for item in flattened if counts[item] > 1]



Sample Correct Code:
def extract_singly(test_list):
  res = []
  temp = set()
  for inner in test_list:
    for ele in inner:
      if not ele in temp:
        temp.add(ele)
        res.append(ele)
  return (res) 


Asserts:
assert extract_singly([(3, 4, 5), (4, 5, 7), (1, 4)]) == [3, 4, 5, 7, 1]
assert extract_singly([(1, 2, 3), (4, 2, 3), (7, 8)]) == [1, 2, 3, 4, 7, 8]
assert extract_singly([(7, 8, 9), (10, 11, 12), (10, 11)]) == [7, 8, 9, 10, 11, 12]


Tests:
Test 1 of 3: FAIL: AssertionError()

Test 140 of 974: 101/140 (72.14285714285714%): failed