<｜begin▁of▁sentence｜>### Instruction:
As a networkx assistant, I can help you conceptualize the DiffusionTreeSampler usage in a manner that is closely aligned with your scenario. The DiffusionTreeSampler is like a tool used for soil sampling to investigate soil properties and composition to improve agricultural productivity or land management practices. Given a networkx erdos_renyi_graph with parameters n=200, p=0.25, you want to use the DiffusionTreeSampler to sample a subgraph utilizing a diffusion process initiated from a specific node, and then determine the number of nodes in the sampled graph.
### Response:
import networkx as nx
from littleballoffur import DiffusionTreeSampler

G = nx.gnp_random_graph(n=200, p=0.25)

sampler = DiffusionTreeSampler(seed=10)

sampler_G = sampler.sample(G, start_node=0)

print(len(sampler_G))
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