class_docstr: Special keyword value.
  
  The instance of this class may be used as the default value assigned to a
  deprecated keyword in order to check if it has been given a user defined
  value.
code: def __new__(cls):
      # ensure that only one instance exists
      if not cls.__instance:
          cls.__instance = super(_NoValueType, cls).__new__(cls)
      return cls.__instance
  
file_path: catboost/contrib/python/numpy/py2/numpy/_globals.py
imports: from __future__ import division, absolute_import, print_function
label_desc: Use image node_id 1 for calling the _NoValueType obj's underlying member method code with example usage: obj.__new__(cls) and returns: cls