docstr: We use a callable class to be able to change the ``__repr__``.
code: def __call__(self, inst, attr, value):
      """
      We use a callable class to be able to change the ``__repr__``.
      """
      if not callable(value):
          message = (
              "'{name}' must be callable "
              "(got {value!r} that is a {actual!r})."
          )
          raise NotCallableError(
              msg=message.format(
                  name=attr.name, value=value, actual=value.__class__
              ),
              value=value,
          )
  
imports: from __future__ import absolute_import, division, print_function
  import re
  from ._make import _AndValidator, and_, attrib, attrs
  from .exceptions import NotCallableError
label_desc: Use image node_id 1 for calling the _IsCallableValidator obj's underlying member method code with example usage: obj.__call__(inst, attr, value) without return types