[Tutor] python's default argument value handling in functions - weird syntax? problem grappling with the concept

[Mike Bell]

The function's local variable L is not static, but "default argument
value" is, which is what the documentation means when it says that it
will evaluate these only once.  When the default value is a list (in
your code, not "the empty list" but a list which happens to be empty
when the default arguments are being evaluated), that same object is
used every time the function is called.

mike