👉 In programming, a defaiency is an error or condition that occurs when a function does not return a value. In other words, if a function is called but it returns None or an empty list, the function will be considered as a defaiency and the program will raise an exception. For example: ```python def add(a, b): return a + b try: print(add(5, 0)) # This will raise a ValueError because the second argument is