class_docstr: "Probability Mixin
  
  Mixin for probability features on objects
  interfacing with :class:`~mlens.parallel.backend.ParallelProcessing`
  
  .. note::
     To use this mixin the instance inheriting it must set the ``proba``
     and the ``_classes(=None)``attribute in ``__init__``.
docstr: Set classes given input y
docstr_tok: ["Set","classes","given","input","y"]
code: def classes_(self, y):
      """Set classes given input y"""
      self._classes = np.unique(y).shape[0]
  
imports: import warnings
  from abc import abstractmethod
  import numpy
  from ._base_functions import check_stack, check_params
  from ..None import config
  from ..utils.exceptions import ParallelProcessingError
  from ..externals.sklearn.base import clone, BaseEstimator
label_desc: Use image node_id 5 for calling the ProbaMixin obj's underlying member method code with example usage: obj.classes_(y) without return types