<｜begin▁of▁sentence｜>### Instruction:
How can you use `AbstractCairoDrawer.__init__()` to create a drawer for plotting an igraph object, given a sample tree graph with 5 vertices, branching factor of 2 and you want to draw it within a 400x400 bounding box?
### Response:
import igraph as ig
from igraph.drawing import Plot, BoundingBox
from igraph.drawing.graph import DefaultGraphDrawer

# Creating a sample igraph graph
g = ig.Graph.Tree(5, 2)

# Create a BoundingBox instance
canvas_bbox = BoundingBox(400, 400)

# Create a plot instance with the bounding box
plot = Plot(bbox=canvas_bbox, target='output.png')

# Create Drawer
ctx = plot.context
graph_drawer = DefaultGraphDrawer(ctx, bbox=canvas_bbox)

# Draw the graph onto the plot
g.add_vertices(3)
g.add_edges([(0, 1), (1, 2)])
graph_drawer.draw(g)

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