def get_dependencies(self, ctx):
        node_state = self._get_state(ctx)
        results = []
        for ctx_id, callees in node_state.callees.iteritems():
            ctx = _get_context(ctx_id, ctx)
            for callee in callees:
                results.append((callee, ctx))
        return results
returns a list of (node, ctx) that this node is dependent on
dataset/ETHPy150Open manahl/mdf/mdf/nodes.py/MDFNode.get_dependencies