<｜begin▁of▁sentence｜>### Instruction:
Given a directed graph stored in a GML file 'graph.gml', and a specific vertex index of 4, can you find and list the predecessor vertices of the specified vertex using the igraph library?
### Response:
import igraph as ig

# Load a graph from a file
g = ig.Graph.Read_GML('graph.gml')

# Choose a vertex index for which you want to find predecessors
vertex_idx = 4

# Get the predecessors of the chosen vertex
predecessors = g.predecessors(vertex_idx)

print('Predecessors of vertex {}: {}'.format(vertex_idx, predecessors))
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