Interview Q&A / Python

1. What are *args and **kwargs in Python?

   In a function definition, *args collects any extra positional arguments into a tuple, and **kwargs collects any extra keyword arguments into a dict. They let a function accept a variable number of inputs. The same * and ** symbols also unpack a list or dict when calling a function.

   BeginnerIn-depth3 min read
2. What are mutable and immutable objects in Python, and why is a mutable default argument a bug?

   Mutable objects such as lists, dicts and sets can change in place; immutable ones such as int, str and tuple cannot. Default arguments are evaluated once, when the function is defined, so a list used as a default is shared across every call. Use None as the default and create the list inside the function.

   BeginnerIn-depth3 min read
3. What is a lambda function in Python, and what are its limits?

   A lambda is a small anonymous function written as lambda args: expression. It contains a single expression, returns its value automatically and cannot hold statements. It is handy as a short key or callback.

   BeginnerQuick answer1 min read
4. What is the LEGB rule in Python?

   LEGB is the order in which Python looks up a name: Local, Enclosing (outer functions), Global (module), then Built-in. The first scope that contains the name wins, and if none do, Python raises NameError.

   BeginnerQuick answer1 min read