As per the Python’s Official Documentation, set data structure is referred as Unordered Collections of Unique Elements and that doesn’t support operations like indexing or slicing etc.
Like other collections, sets support x in set, len(set), and for x in set. Being an unordered collection, sets do not record element position or order of insertion. Accordingly, sets do not support indexing, slicing, or other sequence-like behavior.
When you define temp_set = {1, 2, 3} it just implies that temp_set contains 3 elements but there’s no index that can be obtained
>>> temp_set = {1,2,3}
>>> 1 in temp_set
>>> True
>>> temp_set[0]
>>> Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/IPython/core/interactiveshell.py", line 3326, in run_code
exec(code_obj, self.user_global_ns, self.user_ns)
File "<ipython-input-10-50885e8b29cf>", line 1, in <module>
temp_set[0]
TypeError: 'set' object is not subscriptable