The categories of this categorical.
Setting assigns new values to each category (effectively a rename of each individual category).
The assigned value has to be a list-like object. All items must be unique and the number of items in the new categories must be the same as the number of items in the old categories.
Assigning to categories is a inplace operation!
If the new categories do not validate as categories or if the number of new categories is unequal the number of old categories