<｜begin▁of▁sentence｜>### Instruction:
As a machine learning engineer, you have been tasked with creating a visualization of a complex machine learning model for a presentation to stakeholders. You are using igraph library to generate the visual representation, and now need to implement a feature to add text to the visualization. The requirement is to utilize the CairoTextDrawer with a Cairo context to draw the text 'Hello, world!' at specific coordinates on the visual representation and then save the output as a PNG file for incorporation into the presentation. Can you provide the steps to achieve this objective using the igraph library?
### Response:
from igraph.drawing import CairoTextDrawer
import cairo

# Create a Cairo surface and context to draw on
canvas_surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 200, 200)
context = cairo.Context(canvas_surface)

text_drawer = CairoTextDrawer(context, halign=cairo_text_drawer.HALIGN_LEFT, valign=cairo_text_drawer.VALIGN_TOP)
text_drawer.draw_text(10, 10, 'Hello, world!')

# Save the drawing to a PNG file
canvas_surface.write_to_png('text_example.png')
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