text: from euler.primes import naive, erat2, erat2a, psieve, erat3
  from itertools import islice
  
  
  PRIMES_TWENTY = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71]
  
  
  def test_naive():
      primes = naive
      assert list(islice(primes(), 20)) == PRIMES_TWENTY
  
  
  def test_erat2():
      primes = erat2
      assert list(islice(primes(), 20)) == PRIMES_TWENTY
  
  
  def test_erat2a():
      primes = erat2a
      assert list(islice(primes(), 20)) == PRIMES_TWENTY
  
  
  def test_psieve():
      primes = psieve
      assert list(islice(primes(), 20)) == PRIMES_TWENTY
  
  
  def test_erat3():
      primes = erat3
      assert list(islice(primes(), 20)) == PRIMES_TWENTY
  