Can a tuple be used as a unique identifier in a dictionary or set?

Yes, a tuple can be used as a unique identifier in a dictionary or set because it is an immutable data type in Python. This allows tuples to be used as dictionary keys or set elements.

Example:

my_dict = {}
key = (1, 'a', 3.14)
my_dict[key] = "value"

my_set = set()
my_set.add(key)

print(my_dict[key])  # Outputs: value
print(key in my_set)  # Outputs: True

It is important that all elements within the tuple are also hashable; otherwise, the tuple cannot be used as a key.