<｜begin▁of▁sentence｜>### Instruction:
As a news anchor presenting a technology segment, you might report on the creation of a visualization using the igraph and Cairo graphics library APIs. In this scenario, you could discuss creating a vertex drawer in igraph using the Cairo graphics library to visually represent a hierarchical network structure from a real-world dataset. The segment could include instructions on labeling each vertex with its id and saving the resulting plot to a PDF file for further analysis and presentation.
### Response:
import igraph as ig
from igraph.drawing import Plot
from igraph.drawing.cairo import CairoVertexDrawer, BoundingBox

# Create a graph
g = ig.Graph.Tree(3, 2)

# Define the layout
layout = g.layout('auto')

# Set up Cairo plot with a specific size
plot = Plot(bbox=(0, 0, 300, 300))

# Create a vertex drawer with the plot's context and bounding box
vertex_drawer = CairoVertexDrawer(plot.context, plot.bbox, plot.palette, layout)

# Draw the vertices
g.vs['label'] = range(len(g.vs))  # Label vertices with their ids
vertex_drawer.draw(g.vs)

# Save the plot to a file
plot.save('tree_graph.pdf')
<|EOT|>
