Reverse a string

Write a function reverse_string that receives a string and returns it reversed. Example:

reverse_string('Hello World')  # 'dlroW olleH'
reverse_string('Python')  # nohtyP
import unittest


class ReverseTestCase(unittest.TestCase):

    def test_with_large_string(self):
        self.assertEqual(reverse_string('Python is Awesome'),
                         'emosewA si nohtyP')

    def test_with_short_string(self):
        self.assertEqual(reverse_string('Python'), 'nohtyP')