In the third case, there a two seperate itertos created with a deep clone.

In the third case, there a two seperate iterators created with a deep clone.

import copy my_list = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"] class my_enumerate: def __init__(self, container): self.counter = 0 self.iterator = iter(container) def __next__(self): self.counter += 1 return self.counter - 1, next(self.iterator) def iterate_5_elements(iterator): for _ in range(5): print(next(iterator)) my_iterator1 = my_enumerate(my_list) iterate_5_elements(my_iterator1) iterate_5_elements(my_iterator1) print("--------------------------------") my_iterator2 = my_enumerate(my_list) # Each copy has it's own counter but a reference to the same iterator. # Both shallow copies use the same iterator. iterate_5_elements(copy.copy(my_iterator2)) iterate_5_elements(copy.copy(my_iterator2)) print("--------------------------------") my_iterator3 = my_enumerate(my_list) iterate_5_elements(copy.deepcopy(my_iterator3)) iterate_5_elements(copy.deepcopy(my_iterator3)) print("--------------------------------") 

import copy my_list = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"] class my_enumerate: def __init__(self, container): self.counter = 0 self.iterator = iter(container) def __next__(self): self.counter += 1 return self.counter - 1, next(self.iterator) def iterate_5_elements(iterator): for _ in range(5): print(next(iterator)) my_iterator1 = my_enumerate(my_list) iterate_5_elements(my_iterator1) iterate_5_elements(my_iterator1) print("--------------------------------") # Each copy has its own counter but a reference to the same iterator. # Both shallow copies use the same iterator. my_iterator2 = my_enumerate(my_list) my_iterator2_copy1 = copy.copy(my_iterator2) my_iterator2_copy2 = copy.copy(my_iterator2) iterate_5_elements(my_iterator2_copy1) iterate_5_elements(my_iterator2_copy2) print("Same inner iterator:", my_iterator2_copy1.iterator is my_iterator2_copy2.iterator) print("--------------------------------") # Each copy has its own counter and a reference to a seperate iterator. # Both deep copies use seperate iterators. my_iterator3 = my_enumerate(my_list) my_iterator3_copy1 = copy.deepcopy(my_iterator3) my_iterator3_copy2 = copy.deepcopy(my_iterator3) iterate_5_elements(my_iterator3_copy1) iterate_5_elements(my_iterator3_copy2) print("Same inner iterator:", my_iterator3_copy1.iterator is my_iterator3_copy2.iterator) print("--------------------------------") 

Output:

(0, 'a') (1, 'b') (2, 'c') (3, 'd') (4, 'e') (5, 'f') (6, 'g') (7, 'h') (8, 'i') (9, 'j') -------------------------------- (0, 'a') (1, 'b') (2, 'c') (3, 'd') (4, 'e') (0, 'f') (1, 'g') (2, 'h') (3, 'i') (4, 'j') Same inner iterator: True -------------------------------- (0, 'a') (1, 'b') (2, 'c') (3, 'd') (4, 'e') (0, 'a') (1, 'b') (2, 'c') (3, 'd') (4, 'e') Same inner iterator: False --------------------------------