what should be the order of class names in sklearn tree export function (Beginner question on python sklearn)
The names should be given in ascending numerical order.

Saw this in the code's docs:

class_names : list of strings, bool or None, optional (default=None)
    Names of each of the target classes in ascending numerical order.
    Only relevant for classification and not supported for multi-output.
    If ``True``, shows a symbolic representation of the class name.