<｜begin▁of▁sentence｜>### Instruction:
Given a graph with a custom 'attribute_collector' attached to its vertices, can you find out how many attributes have been collected using the '__len__' method from the 'AttributeCollectorBase' class?
### Response:
from igraph import Graph

# Load or create a graph
g = Graph.Erdos_Renyi(n=100, m=200)

# Assume 'AttributeCollectorBase' is part of a given class for collecting attributes
collector = g.vs['attribute_collector']

# Get the number of collected attributes
number_of_attributes = len(collector)

print(number_of_attributes)
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