digraph G {
   node_0 [label="1: 1"]
   node_2 [label="3: 11"]
   node_1 [label="2: 10"]
   node_6 [label="7: 111"]
   node_5 [label="6: 110"]
   node_4 [label="5: 101"]
   node_3 [label="4: 100"]

   node_14 [label="15: 1111"]
   node_13 [label="14: 1110"]
   node_12 [label="13: 1101"]
   node_11 [label="12: 1100"]
   node_10 [label="11: 1011"]
   node_9 [label="10: 1010"]
   node_8 [label="9: 1001"]
   node_7 [label="8: 1000"]
   node_1 -> node_3 [label="r"]
   node_1 -> node_5 [label="l"]
   node_0 -> node_2 [label="l"]
   node_0 -> node_1 [label="r"]
   node_2 -> node_4 [label="r"]
   node_2 -> node_6 [label="l"]
   node_3 -> node_11 [label="l"]
   node_3 -> node_7 [label="r"]
   node_4 -> node_12 [label="l"]
   node_4 -> node_8 [label="r"]
   node_5 -> node_13 [label="l"]
   node_5 -> node_9 [label="r"]
   node_6 -> node_10 [label="r"]
   node_6 -> node_14 [label="l"]
}