def test_termial_function_solution_zero(self) -> None:
"""Test solution to termial function when x is set to zero."""
assert State._termial_function_solution(0) == 0
def test_termial_function_solution(self, n: int) -> None:
"""Test solution to termial function."""
x = State._termial_function(n)
assert State._termial_function_solution(
x - 1) <= n <= State._termial_function_solution(x)