<｜begin▁of▁sentence｜>### Instruction:
Given a graph with a path from node 1 to node 3 where each edge has a 'color' attribute set to 'red', and an additional edge from node 3 to node 4 without a specified color, can you retrieve the color attributes for all edges in the graph, using 'blue' as the default color for edges that do not have the attribute set?
### Response:
import networkx as nx

# Create a graph
G = nx.Graph()

# Add edges with an attribute 'color'
nx.add_path(G, [1, 2, 3], color='red')

# Retrieve the 'color' attribute of all edges
edge_colors = nx.get_edge_attributes(G, 'color')

# Print the color attribute of edge (1, 2)
print(edge_colors[(1, 2)])

# Add an edge without the 'color' attribute
G.add_edge(3, 4)

# Retrieve the 'color' attribute of all edges,
# specifying 'blue' as the default for edges without this attribute
edge_colors = nx.get_edge_attributes(G, 'color', default='blue')

# Print the color attribute of edge (3, 4),
# which was not originally assigned a color, hence the default is used.
print(edge_colors[(3, 4)])
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