<｜begin▁of▁sentence｜>### Instruction:
As a nuclear engineer, you are responsible for designing, developing, operating, and maintaining nuclear systems for various applications such as energy production, medical diagnosis and treatment, scientific research, industrial processes, or national security. One of your important tasks is to ensure safety, security, reliability, and regulatory compliance in order to harness nuclear energy, advance nuclear science, and address societal needs and challenges.

In this context, imagine you are working on a nuclear research program that involves collaboration with multiple experts in the field. You have a coauthorship graph representing the network of researchers involved, stored in a GML file named netscience.gml. Additionally, you have a file in JSON format named communities.json, which contains the list of communities identified within this coauthorship network.

Your task is to utilize the CDlib library's function read_community_json to read the list of communities from the JSON file. After reading the communities from the JSON file, you need to determine the total number of nodes across all communities. This information will assist in understanding the distribution of researchers across different collaborative groups within the network.
### Response:
import networkx as nx
from cdlib import readwrite

# Read the network science coauthorship graph
G = nx.read_gml('netscience.gml')

# Read community list from JSON file
communities = readwrite.read_community_json('communities.json')

# Now you have the communities loaded from the file and you can work with them
debug_size = sum(len(c) for c in communities.communities)
print(f'Total number of nodes in all communities: {debug_size}')
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