Write a function to count bidirectional tuple pairs.
def count_bidirectional(test_list):
  res = 0
  for idx in range(0, len(test_list)):
    for iidx in range(idx + 1, len(test_list)):
      if test_list[iidx][0] == test_list[idx][1] and test_list[idx][1] == test_list[iidx][0]:
        res += 1
  return (str(res)) 
<s>[INST]<<SYS>>Given a task and its code, generate test cases for the code.<</SYS>>Write a function to count bidirectional tuple pairs.
def count_bidirectional(test_list):
  res = 0
  for idx in range(0, len(test_list)):
    for iidx in range(idx + 1, len(test_list)):
      if test_list[iidx][0] == test_list[idx][1] and test_list[idx][1] == test_list[iidx][0]:
        res += 1
  return (str(res)) [/INST]assert count_bidirectional([(5, 6), (1, 2), (6, 5), (9, 1), (6, 5), (2, 1)] ) == '3'
assert count_bidirectional([(5, 6), (1, 3), (6, 5), (9, 1), (6, 5), (2, 1)] ) == '2'
assert count_bidirectional([(5, 6), (1, 2), (6, 5), (9, 2), (6, 5), (2, 1)] ) == '4'</s>