def test_twice_as_many_ints(x):
"""Test the number of integers resulting from duplicate.
"""
assert num_ints(duplicate(x)) == 2 * num_ints(x)
def test_duplicate_doctest():
"""Test the doctest example for duplicate."""
nested_list = [1, [2, 3]]
expected = [1, 1, [2, 2, 3, 3]]
assert duplicate(nested_list) == expected
def test_handles_integers(x):
"""Test duplicate when given an integer."""
assert duplicate(x) == [x, x]