https://stackoverflow.com/questions/1132941/the-mutable-default-argument-in-python https://stackoverflow.com/questions/1132941/the-mutable-defa... and https://w

https://stackoverflow.com/questions/1132941/the-mutable-default-argument-in-python https://stackoverflow.com/questions/1132941/the-mutable-defa... and https://www.valentinog.com/blog/tirl-python-default-arguments/ https://www.valentinog.com/blog/tirl-python-default-argument... basically, having a default argument value in a function definition means to evaluate it during definition time of that function, not when the function is invoked. This is a foot gun.