def test_get_free_symbols_indexed(self):
expr = a_[i] * IndexedBase(a * b)[j]
self.assert_symbol_sets_equal({a, b, i, j},
set(get_free_symbols(expr)))
def test_get_free_symbols(self):
expr = a * b / 5
self.assert_symbol_sets_equal([a, b], get_free_symbols(expr))
