<｜begin▁of▁sentence｜>### Instruction:
Given a graph of books about US politics, which you can read from a GML file named polbooks.gml, can you use the head_tail function in cdlib with a head/tail ratio of 0.8 to perform community detection? And can you convert the detected communities into a JSON representation?
### Response:
import networkx as nx
from cdlib import algorithms

# Create a simple graph from the polbooks dataset
G = nx.read_gml('polbooks.gml')

# Apply the head/tail breaks community detection algorithm with a defined head/tail ratio
communities = algorithms.head_tail(G, head_tail_ratio=0.8)

# Convert the communities to a JSON object
communities_json = communities.to_json()

print(communities_json)
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