'Determine whether or not a frame attribute has its value because it\'s
the default value, or because this frame was created with that value
explicitly requested.
Parameters
attrnm : str
The name of the attribute to check.
Returns
isdefault : bool
True if the attribute ``attrnm`` has its value by default, False if
it was specified at creation of this frame.'

def is_frame_attr_default(self, attrnm):

    return (attrnm in self._attr_names_with_defaults)
