<｜begin▁of▁sentence｜>### Instruction:
As an Intensive Care Nurse, you are managing a team responsible for updating the graphical representation of patient data within the hospital's information system. You need to create a simple tree graph representation of patient records using Python's NetworkX library. The graph should consist of 3 nodes, with each node having 2 child nodes, indicating the patient's medical history and vital statistics. Once created, the graph should be saved as 'tree.png' with a size of 300x300 pixels and a margin of 20 units for clear visualization.
### Response:
from igraph import Graph, plot

# Create a simple graph
g = Graph.Tree(3, 2)

# Plot the graph
g_plot = plot(g, target='tree.png', bbox=(300, 300), margin=20)
print('The graph has been saved as tree.png')
<|EOT|>
