<｜begin▁of▁sentence｜>### Instruction:
As a network data analyst, I'm often tasked with analyzing graph data to extract useful insights. For instance, today a client has provided me with a GraphML file named 'network_data.graphml', which contains a single graph with integer node identifiers. I need to use NetworkX, a Python library for analyzing complex networks, to read the graph and determine the number of nodes it contains. This will help me better understand the size and complexity of the network and make informed decisions about further analysis.
### Response:
from networkx import read_graphml

# Read a graph from a GraphML file
graph = read_graphml('network_data.graphml', node_type=int)

# Get the number of nodes in the graph
number_of_nodes = graph.number_of_nodes()

# Print the number of nodes
print(number_of_nodes)
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