<｜begin▁of▁sentence｜>### Instruction:
Given a weighted graph that you can read from example.gml, can you calculate the strength (weighted degree) for a specified vertex or group of vertices using the strength function in igraph?
### Response:
import igraph as ig

# Reading from an example GML file
g = ig.read('example.gml')

# Calculating the strength for vertex with ID 2
vertex_strength = g.strength(vertices=2, weights='weight', mode='all', loops=True)
print('Strength of vertex 2:', vertex_strength)

# Calculating the strength for multiple vertices, IDs 2, 3, and 5
group_strength = g.strength(vertices=[2, 3, 5], weights='weight', mode='all', loops=True)
print('Strengths of vertices 2, 3, and 5:', group_strength)
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