class_docstr: Policy Object basic framework.
  
  This class is useless unless subclassed.  A subclass should define
  class attributes with defaults for any values that are to be
  managed by the Policy object.  The constructor will then allow
  non-default values to be set for these attributes at instance
  creation time.  The instance will be callable, taking these same
  attributes keyword arguments, and returning a new instance
  identical to the called instance except for those values changed
  by the keyword arguments.  Instances may be added, yielding new
  instances with any non-default values from the right hand
  operand overriding those in the left hand operand.  That is,
  
      A + B == A(<non-default values of B>)
  
  The repr of an instance can be used to reconstruct the object
  if and only if the repr of the values can be used to reconstruct
  those values.
code: def __repr__(self):
      args = [
          "{}={!r}".format(name, value)
          for name, value in self.__dict__.items()
      ]
      return "{}({})".format(self.__class__.__name__, ", ".join(args))
  
imports: import abc
  from email import header
  from email import charset
  from email.utils import _has_surrogates
label_desc: Use image node_id 2 for calling the _PolicyBase obj's underlying member method code with example usage: obj.__repr__() and returns: str