<｜begin▁of▁sentence｜>### Instruction:
Given a graph which you can read from graph_data.gml, can you use the cohesive_blocks function in igraph to get the cohesive block structure of the graph and print it for each level?
### 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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