<｜begin▁of▁sentence｜>### Instruction:
Given a tree graph with 5 vertices and a branching factor of 2, can you use the CairoArrowEdgeDrawer in igraph to draw undirected edges and save the graph as a PNG image?
### Response:
from igraph.drawing import Plot
from igraph.drawing.edge import CairoArrowEdgeDrawer
import igraph as ig

# Create a graph
g = ig.Graph.Tree(5, 2)  # Tree with 5 vertices and branching factor of 2

# Initialize plot
plot = Plot(bbox=(300, 300), background='white')

# Add vertices to the plot
plot.add(g)

# Use CairoArrowEdgeDrawer to draw the undirected edges
edge_drawer = CairoArrowEdgeDrawer(plot.context)
for edge in g.es:
    from_pt = plot.coords[edge.source]
    to_pt = plot.coords[edge.target]
    edge_drawer.draw_undirected_edge(from_pt, to_pt)

# Save the plot
g.save('tree_graph.png')
<|EOT|>
