def METHOD_NAME(self):
    """
    Verify output types and lengths.
    first_name()       - str
    first_name(num=3)  - list of length 3
    first_name(gender='f') - str
    first_name(return_list=True) - list of length 1
    """
    single_name = namegen.first_name()
    self.assertEqual(type(single_name), str)
    three_names = namegen.first_name(num=3)
    self.assertEqual(type(three_names), list)
    self.assertEqual(len(three_names), 3)
    gendered_name = namegen.first_name(gender="f")
    self.assertEqual(type(gendered_name), str)
    single_list = namegen.first_name(return_list=True)
    self.assertEqual(type(single_list), list)
    self.assertEqual(len(single_list), 1)
    with self.assertRaises(ValueError):
        namegen.first_name(gender="x")
    with self.assertRaises(ValueError):
        namegen.first_name(num=-1)