code: def default_if_none(default=NOTHING, factory=None):
      """
      A converter that allows to replace ``None`` values by *default* or the
      result of *factory*.
  
      :param default: Value to be used if ``None`` is passed. Passing an instance
         of `attr.Factory` is supported, however the ``takes_self`` option
         is *not*.
      :param callable factory: A callable that takes no parameters whose result
         is used if ``None`` is passed.
  
      :raises TypeError: If **neither** *default* or *factory* is passed.
      :raises TypeError: If **both** *default* and *factory* are passed.
      :raises ValueError: If an instance of `attr.Factory` is passed with
         ``takes_self=True``.
  
      .. versionadded:: 18.2.0
      """
      if default is NOTHING and factory is None:
          raise TypeError("Must pass either `default` or `factory`.")
  
      if default is not NOTHING and factory is not None:
          raise TypeError(
              "Must pass either `default` or `factory` but not both."
          )
  
      if factory is not None:
          default = Factory(factory)
  
      if isinstance(default, Factory):
          if default.takes_self:
              raise ValueError(
                  "`takes_self` is not supported by default_if_none."
              )
  
          def default_if_none_converter(val):
              if val is not None:
                  return val
  
              return default.factory()
  
      else:
  
          def default_if_none_converter(val):
              if val is not None:
                  return val
  
              return default
  
      return default_if_none_converter
  
imports: from __future__ import absolute_import, division, print_function
  from ._compat import PY2
  from ._make import NOTHING, Factory, pipe
label_desc: Use image node_id 2 for calling a global function with example usage: default_if_none(default, factory) and returns: default_if_none_converter, default, default, val, val