<｜begin▁of▁sentence｜>### Instruction:
As a chauffeur who drives vehicles to transport passengers, imagine you're tasked with optimizing your routes for efficiency. Suppose you have a map of the city's road network represented as a graph, with each edge denoting a road connecting two intersections. Now, you're curious about finding the maximum number of passengers you can pick up at once while traversing the city. In simpler terms, you want to know the largest group of intersections where each intersection is directly connected to every other intersection in that group via roads. To solve this, you're considering using the `clique_number` function from the igraph API, which can help identify these optimal clusters of intersections where you can efficiently pick up passengers.
### Response:
from igraph import Graph

# Define a graph
edges = [(0, 1), (0, 2), (1, 2), (1, 3), (2, 3), (3, 4), (4, 5)]
g = Graph(edges=edges)

# Calculate the clique number
clique_num = g.clique_number()

# Print the clique number
print('The clique number of the graph is:', clique_num)
<|EOT|>
