<｜begin▁of▁sentence｜>### Instruction:
Given a path graph of 4 nodes where the first and last nodes are labeled 'A' and 'B' respectively, how can the node_classification.harmonic_function in NetworkX be used to predict the labels for the unlabeled nodes?
### Response:
import networkx as nx
from networkx.algorithms import node_classification

# Create a path graph
G = nx.path_graph(4)
# Assign labels to the end nodes
G.nodes[0]['label'] = 'A'
G.nodes[3]['label'] = 'B'
# Predict labels for the unlabeled nodes
predicted_labels = node_classification.harmonic_function(G)
print('Predicted labels:', predicted_labels)
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