<｜begin▁of▁sentence｜>### Instruction:
Imagine that you're the master baker crafting a multi-tiered cake, and each tier of the cake represents a different level in your bakery's network of supply routes. You start with the base tier, which is your supplier node 0. From there, each subsequent tier links to the next set of suppliers. As you plan out the logistics for your bakery, you're particularly interested in identifying those suppliers who are two steps away in the network from the base tier—those would be the suppliers who are directly connected to the ones on the level just above them, but not directly connected to the base. In the recipe book of your supply chain, you've got a list [(0,1),(0,2),(1,3),(1,4),(2,5),(2,6)] that charts out which suppliers connect to which. Using this guide, can you determine which suppliers are situated on the second tier from the base in your bakery’s distribution network?
### Response:
import networkx as nx

# Create a Direct Graph
digraph = nx.DiGraph()
# Add edges (nodes are added automatically)
digraph.add_edges_from([(0,1),(0,2),(1,3),(1,4),(2,5),(2,6)])

# Use descendants_at_distance to find all nodes at a fixed distance from a source node
# In this case, we want to find all nodes that are at a distance of 2 from node 0
descendants = nx.descendants_at_distance(digraph, 0, 2)
print(descendants)  # Output: {3, 4, 5, 6}
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