def _nodes_slots_to_slots_nodes(self, mapping):
        """
        Converts a mapping of
        {id: <node>, slots: (slot1, slot2)}
        to
        {slot1: <node>, slot2: <node>}

        Operation is expensive so use with caution
        """
        out = {}
        for node in mapping:
            for slot in node['slots']:
                out[str(slot)] = node['id']
        return out
Converts a mapping of
        {id: <node>, slots: (slot1, slot2)}
        to
        {slot1: <node>, slot2: <node>}

        Operation is expensive so use with caution