<｜begin▁of▁sentence｜>### Instruction:
As a hydrologist studying water cycles for water resource management, you might be interested in understanding the connectivity patterns within different bodies of water. Given two river networks, one with 10 tributaries and 20 connections and the other with 5 tributaries and 10 connections, you may want to utilize the count_subisomorphisms_vf2 function in networkx to determine how many subisomorphisms exist from the smaller river network to the larger one, without considering specific characteristics of the tributaries or connections. This analysis could provide insights into the overall connectivity and flow patterns within the river systems.
### Response:
from igraph import Graph

def count_subisomorphisms(g1, g2, color1=None, color2=None, edge_color1=None, edge_color2=None):
    return g1.count_subisomorphisms_vf2(g2, color1=color1, color2=color2, edge_color1=edge_color1, edge_color2=edge_color2)

# Example usage
# Create two graphs
graph1 = Graph.Erdos_Renyi(n=10, m=20)
graph2 = Graph.Erdos_Renyi(n=5, m=10)

# Count the number of subisomorphisms from graph2 to graph1 without any color restrictions
count = count_subisomorphisms(graph1, graph2)
print('Number of subisomorphisms:', count)
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