<｜begin▁of▁sentence｜>### Instruction:
Given a graph representing Books about US politics, where nodes represent books and edges represent frequent co-purchasing by the same buyers, stored in a file named polbooks.gml, can you use the Louvain method to detect communities and then compute the link modularity for the resulting community structure?
### Response:
import networkx as nx
from cdlib import algorithms, evaluation

# Creating a graph from a GML file
G = nx.read_gml('polbooks.gml')

# Detecting communities with the Louvain method
communities = algorithms.louvain(G)

# Calculating link modularity
link_modularity_value = evaluation.link_modularity(G, communities)

# Printing the link modularity
print('Link modularity:', link_modularity_value.score)
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