Do not use a mutable like `list` or `dictionary` as a default value to an argument. Python’s default arguments are evaluated once when the function is defined. Using a mutable default argument and mutating it will mutate that object for all future calls to the function as well.
The use of `else` or `elif` becomes redundant and can be dropped if the last statement under the leading `if` / `elif` block is a `return` statement.
In the case of an `elif` after `return`, it can be written as a separate `if` block.
For `else` blocks after `return`, the statements can be shifted out of `else`. Please refer to the examples below for reference.
Refactoring the code this way can improve code-readability and make it easier to maintain.
