<｜begin▁of▁sentence｜>### Instruction:
Given a joint degree dictionary with the following structure: {1: {4: 1}, 4: {1: 1, 2: 2}, 2: {4: 2}}, where the entry joint_degrees[k][l] is the number of edges joining nodes of degree k with nodes of degree l, can you determine if such a joint degree dictionary is realizable as a simple graph using NetworkX?
### Response:
import networkx as nx

# Define a joint degree dictionary
joint_degrees = {1: {4: 1}, 4: {1: 1, 2: 2}, 2: {4: 2}}

# Check if the joint degree is realizable as a simple graph
is_realizable = nx.is_valid_joint_degree(joint_degrees)

print('Is the joint degree dictionary realizable?', is_realizable)
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