unit questions

`String.prototype.codePointAt` returns an integer representing the UTF-16 code unit at a specified index in a string. It is useful for dealing with Unicode characters. 

const str = '𠮷';
const codePoint = str.codePointAt(0);
console.log(codePoint); // 134071

`String.fromCharCode` returns a string created from the specified sequence of UTF-16 code units. It is used to convert code units to characters. 

const char = String.fromCharCode(65);
console.log(char); // 'A'

Django includes a testing framework based on Python's `unittest` module. You write test cases by creating classes that inherit from `django.test.TestCase`. These tests can simulate requests, check responses, and verify the behavior of your application’s components. Run tests using `python manage.py test` to ensure your application works as expected.

The DATEDIF function calculates the difference between two dates based on a specified unit. For example, =DATEDIF(A1, B1, 'D') returns the number of days between the dates in A1 and B1. You can also use 'M' for months or 'Y' for years. This function is useful for calculating age, tenure, or duration.