docs: def example_instance(cls, skip=()):
          """
          Generate an example instance of a Serializable subclass.
  
          If traits have been tagged with an `example` value, then we use that
          value.  Otherwise we fall back the default_value for the instance.
  
          Traits with names in ``skip`` will not have example values set.
          """
          kwargs = {}
          for name, trait in iteritems(cls.class_traits()):
              if name in skip:
                  continue
              value = trait.example_value
              if value is Undefined:
                  continue
              kwargs[name] = value
  
          return cls(**kwargs)