'Return the current pre-flush change history for
this attribute, via the :class:`.History` interface.
This method **will** emit loader callables if the value of the
attribute is unloaded.
.. seealso::
:attr:`.AttributeState.history`
:func:`.attributes.get_history` - underlying function
.. versionadded:: 0.9.0'

def load_history(self):

    return self.state.get_history(self.key, (PASSIVE_OFF ^ INIT_OK))
