<｜begin▁of▁sentence｜>### Instruction:
As a network visualization expert, ICash Loans has asked you to implement a circular layout visualization of their lending network using the NetworkX library in Python. They want you to create a script that initializes a CairoGraphDrawer with specific dimensions and context, applies a circular layout to the lending network graph, and saves the visualization as a PNG image file. This will help ICash Loans in presenting their lending network in a visually appealing and informative way.
### Response:
from igraph import Graph, plot
from igraph.drawing import BoundingBox
import cairocffi as cairo

# Create an example graph
edges = [(0, 1), (1, 2), (2, 0)]
g = Graph(edges=edges)

# Prepare a Cairo surface to draw on
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 600, 400)
context = cairo.Context(surface)

# Define the bounding box size
bbox = BoundingBox(600, 400)

# Initialize the graph drawer
graph_drawer = Graph.AbstractCairoGraphDrawer(context, bbox)

# Draw the graph
g.to_undirected()
plot(g, target=context, layout=g.layout_circle())

# Save the drawn graph to a file
surface.write_to_png('graph.png')
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