'Returns list of the present positions of the nodes adjacent to node in the given adjacent rank.
@param node node to process
@param adj_rank rank 1 less than the node\'s rank'

def adj_position(self, node, adj_rank):

    pre_level_nodes = self.levels.get(adj_rank, [])
    adj_nodes = []
    if pre_level_nodes:
        for src in pre_level_nodes:
            if (self.transitions.get(src) and (node in self.transitions[src])):
                adj_nodes.append(self.result[src]['y'])
    return adj_nodes
