[pypypypypypy]

It's awesome that someone has taken the time to write this all up. With reference to this section (https://rszalski.github.io/magicmethods/#descriptor) the author mentions that descriptors are "meant to be held by an owner class." which is true, however in their example, they are storing the value as `self.value` on the descriptor object itself meaning that if the user were to have two instances of `Distance` all their values would be the same for meter or foot on all instances of `Distance`. One way to solve this is to store the values in a dictionary-like structure on the descriptor, e.g. `self.data[instance] = your_stored_value`.