def test_atomic():
g, h = map(Function, 'gh')
x = symbols('x')
assert _atomic(g(x + h(x))) == {g(x + h(x))}
assert _atomic(g(x + h(x)), recursive=True) == {h(x), x, g(x + h(x))}
assert _atomic(1) == set()
assert _atomic(Basic(1,2)) == {Basic(1, 2)}
def test_atomic():
g, h = map(Function, 'gh')
x = symbols('x')
assert _atomic(g(x + h(x))) == {g(x + h(x))}
assert _atomic(g(x + h(x)), recursive=True) == {h(x), x, g(x + h(x))}
assert _atomic(1) == set()
assert _atomic(Basic(1, 2)) == {Basic(1, 2)}