<｜begin▁of▁sentence｜>### Instruction:
As an insurance underwriter, you have a graph representing different insurance policy terms, risks, and applications. You need to analyze the cohesive block structure of this graph at each level to ensure that the coverage and premiums for clients are accurately determined. You can leverage the cohesive_blocks function in igraph to achieve this and print the cohesive block structure for each level of the graph.
### Response:
import igraph as ig

# Read a graph from a file
g = ig.read('graph_data.gml')

# Calculate the cohesive blocks of the graph
cohesive_blocks = g.cohesive_blocks()

# Print the cohesive block structure
for level in range(len(cohesive_blocks)):
    print(f'Block level {level}:', cohesive_blocks[level])
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