import unittest;

class Test(unittest.TestCase):
    def test_returns_tuple(self):
        isogram = is_isogram('abolishment')
        self.assertIsInstance(isogram, tuple, msg='Does not return a tuple')

    def test_checks_for_isograms(self):
        word = 'abolishment'
        self.assertEqual(
            is_isogram(word),
            (word, True),
            msg="Isogram word, '{}' not detected correctly".format(word)
        )

    def test_returns_false_for_nonisograms(self):
        word = 'alphabet'
        self.assertEqual(
            is_isogram(word),
            (word, False),
            msg="Non isogram word, '{}' falsely detected".format(word)
        )

    def test_it_only_accepts_strings(self):
        with self.assertRaises(TypeError) as context:
            is_isogram(2)
            self.assertEqual(
                'Argument should be a string',
                context.exception.message,
                'String inputs allowed only'
            )

    def test_empty_string_input(self):
        word = " "
        self.assertEqual(
            is_isogram(word),
            (word, False),
            msg='Empty string not a avalid isogram'
        )


def is_isogram(text):
    if not text:
        return (text,False)
    for letter in text:
      if text.count(letter)==1:
          pass
      else:
          break
    else:
        return (text,True)
    return (text,False)