Is string

Define a function is_string that receives a variable and if it is a string
returns True and if not returns False.

Hint: Use the isinstance function.

Examples:

>>> is_string('happy')
True
>>> is_string(27)
False
import unittest


class IsStringTestCase(unittest.TestCase):

    def test_string(self):
        self.assertEqual(is_string('happy'), True)

    def test_integer(self):
        self.assertEqual(is_string(27), False)