<｜begin▁of▁sentence｜>### Instruction:
As an environmental activist, you're engaged in mapping out ecosystems to better understand and protect them. Imagine you're using a mapping tool like "EcoMap" API, which represents each ecosystem element as a rectangle. These rectangles vary in size, with a standard width of 10 units and a height of 20 units, but they may share these dimensions.

To ensure that each ecosystem element is uniquely identified, you want to implement a custom method within EcoMap that assigns a unique identifier (hash) to each rectangle based on its dimensions. This ensures that even if two rectangles have the same width and height, they will be recognized as distinct entities.

Your task is to develop a custom __hash__ method within the EcoMap API that accurately identifies and counts the number of unique rectangles in the ecosystem map, supporting your efforts in conservation and preservation.
### Response:
import networkx as nx

# Create a simple graph
G = nx.Graph()
G.add_edges_from([(1, 2), (1, 3), (3, 4), (2, 5)])

# Use the __hash__ method from a hypothetical Rectangle module
# Assuming you have a NodeRectangle class that you can associate with graph nodes
class NodeRectangle:
    def __init__(self, width, height):
        self.width = width
        self.height = height
    def __hash__(self):
        return hash((self.width, self.height))

# Assigning rectangles to each node in the graph
for node in G.nodes():
    G.nodes[node]['rect'] = NodeRectangle(width=10, height=20)

# Creating a set to store unique rectangles based on their hash
unique_rectangles = set()
for node, data in G.nodes(data=True):
    unique_rectangles.add(data['rect'])

# Outputting the number of unique rectangles
print('Number of unique rectangles:', len(unique_rectangles))
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