<｜begin▁of▁sentence｜>### Instruction:
As a toxicologist, your expertise lies in understanding the impacts of toxic substances on living organisms and ecosystems. Now, let's say you're investigating the effects of pollutants on a network of interactions within an ecosystem, represented as a graph stored in a file named "graph123.gml".

Your task is to utilize a specialized tool called the "chordal_completion" function provided by the igraph library. This function aids in identifying and adding the necessary connections to the graph to ensure it becomes chordal, meaning that all cycles of length four or more have a chord, or a direct connection between non-adjacent nodes.

Once the chordal_completion function is applied to the graph, your goal is to retrieve and print out the list of edges that were added to achieve chordality. This information will be crucial for understanding how the network structure has been modified to enhance the analysis of pollutant effects on the ecosystem.
### Response:
from igraph import Graph

# Assuming 'g' is an igraph Graph instance you read from a file
# For example, you can read it from 'graph123.gml'
g = Graph.Read_GML('graph123.gml')

# Compute the chordal completion
edges_to_add = g.chordal_completion()

# Add edges to make the graph chordal
for edge in edges_to_add:
    g.add_edge(edge[0], edge[1])

# Print the edges added to make the graph chordal
print('Edges added to make the graph chordal:', edges_to_add)
<|EOT|>
