<｜begin▁of▁sentence｜>### Instruction:
Imagine a local community where the connections between different households are represented by pathways, much like in a neighborhood network. In this scenario, let's say we've mapped out the pathways and identified that households numbered 1 and 2 are on one block, while households numbered 4 and 5 are on another block. The pathways between these blocks are as follows: one leads from household 1 to household 2, another from household 1 to household 3, there's a path linking household 2 to household 3, one more from household 3 to household 4, and finally, a path connecting household 4 to household 5.

Now, in our efforts to understand the ease of access between these two blocks to enhance community health services, we're looking to calculate the 'pathway expansion'—that is, the number of unique pathways that directly connect these two blocks. Could you help us compute the pathway expansion between the block containing households 1 and 2, and the block containing households 4 and 5, using the pathways I've outlined? This would really aid us in planning better health service outreach for the neighborhood.
### Response:
import networkx as nx

# Create a Graph
G = nx.Graph()
G.add_edges_from([(1, 2), (1, 3), (2, 3), (3, 4), (4, 5)])

# Define node sets S and T
S = {1, 2}
T = {4, 5}

# Compute the edge expansion
expansion = nx.edge_expansion(G, S, T)

print('Edge expansion between sets S and T:', expansion)
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