As you remember, the following text leads to an error:

To implement concatenation here, we can just put `20` in quotes, like `"20"`, but this solution doesn't look beautiful program-wise.

Hence, your work will be more fruitful if we can convert everything into strings. Here, the `str()` function should be implemented:

> Note
>
> The syntax of this operation may appear familiar, resembling that of the `int()` or` float()` functions. In reality, it is identical, as it involves converting an argument into a string using the `str()` function.

import unittest


class ExpectedType:
    def __init__(self, expected_type, name):
        self.expected_type = expected_type
        self.name = name


class TestUserCode(unittest.TestCase):
    def _test_variable_equals(self, var_name, expected, expected_type=None):
        import user_code
        if not hasattr(user_code, var_name):
            return (False, f"Expected '{var_name}' variable to be defined.")
        var = getattr(user_code, var_name)

        if (expected_type is not None) and (not isinstance(var, expected_type.expected_type)):
            return (False, f"Expected '{var_name}' to be of type '{expected_type.name}', but got '{type(var).__name__}'.")

        if var != expected:
            return (False, f"Expected '{var_name}' to equal '{expected}', but got '{str(var)}'.")
        return (True, f'The variable {var_name} equals "{expected}"')

    def test_vertices(self):
        passed, result_text = self._test_variable_equals(
            'vertices', '5', expected_type=ExpectedType(str, 'str'))
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    def test_cards(self):
        passed, result_text = self._test_variable_equals(
            'cards', '22', expected_type=ExpectedType(str, 'str'))
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)

    def test_largest_number(self):
        passed, result_text = self._test_variable_equals(
            'largest_number', '128', expected_type=ExpectedType(str, 'str'))
        self._testMethodName = result_text
        self.assertTrue(passed, result_text)


if __name__ == '__main__':
    unittest.main()


test_main.py

This course is going to help you dive deeper into data types and try to work with them. Here you will learn basic operations and all ins and outs of numbers, boolean data type, and strings. This course consists of a lot of practical tasks after which you will become a skillful programmer.

Numeric data types are crucial in Python, so it is important to start with them. Here you will work with simple math operations and find out the purposes of learning different types of numerical data.

The main goal of this section is to clarify the boolean data types; it's a sub type of numeric data, but indeed it is more challenging. Since it is always better to excel in the more difficult topics, this section is a valuable part of your curriculum.

Strings are a way for us to implement your phrases in Python, that is, to give instructions to users who are the target audience of your program. Indeed, it is always better to be able to work with strings because they should be used in your code. You'll understand why soon.

This chapter consists of practical tasks that combine all the examined topics together with a bit of theory.

Converting: str()

Solution