'Preview a StackResource as resources within a Stack.
This method overrides the original Resource.preview to return a preview
of all the resources contained in this Stack.  For this to be possible,
the specific resources need to override both ``child_template`` and
``child_params`` with specific information to allow the stack to be
parsed correctly. If any of these methods is missing, the entire
StackResource will be returned as if it were a regular Resource.'

def preview(self):

    try:
        child_template = self.child_template()
        params = self.child_params()
    except NotImplementedError:
        class_name = reflection.get_class_name(self, fully_qualified=False)
        LOG.warning("Preview    of    '%s'    not    yet    implemented", class_name)
        return self
    name = ('%s-%s' % (self.stack.name, self.name))
    self._nested = self._parse_nested_stack(name, child_template, params)
    return self.nested().preview_resources()
