test_that("is tests work", {
  expect_true(is_twomode(ison_southern_women))
  expect_false(is_directed(ison_southern_women))
  expect_false(is_weighted(ison_southern_women))
  expect_false(is_weighted(ison_southern_women))
  expect_true(is_labelled(ison_southern_women))
  expect_false(is_complex(ison_southern_women))
  expect_true(is_graph(ison_southern_women))
  expect_true(is_manynet(ison_southern_women))
  expect_true(is_graph(ison_southern_women))
  expect_false(is_directed(as_network(ison_southern_women)))
  expect_true(is_connected(ison_southern_women))
  expect_false(is_perfect_matching(ison_southern_women))
  expect_false(is_eulerian(ison_southern_women))
  expect_false(is_acyclic(ison_southern_women))
  expect_false(is_aperiodic(ison_southern_women))
})