class_docstr: Abstract base class for an input validator.
class_docstr_tok: ["Abstract","base","class","for","an","input","validator","."]
docstr: Validate the input.
  If invalid, this should raise a :class:`.ValidationError`.
  
  :param document: :class:`~prompt_toolkit.document.Document` instance.
docstr_tok: ["Validate","the","input",".","If","invalid",",","this","should","raise","a",":","class",":","`",".ValidationError","`",".",":","param","document",":",":","class",":","`","~prompt_toolkit.document.Document","`","instance","."]
code: def validate(self, document):
      """
      Validate the input.
      If invalid, this should raise a :class:`.ValidationError`.
  
      :param document: :class:`~prompt_toolkit.document.Document` instance.
      """
      pass
  
file_path: catboost/contrib/python/prompt-toolkit/py2/prompt_toolkit/validation.py
imports: from __future__ import unicode_literals
  from .filters import to_simple_filter
  from abc import ABCMeta, abstractmethod
  from six import with_metaclass
label_desc: Use image node_id 1 for calling the Validator obj's underlying member method code with example usage: obj.validate(document) without return types