<｜begin▁of▁sentence｜>### Instruction:
Given a directed graph with edge set [(0, 1), (1, 2), (2, 3), (0, 3)], how can you use the dominator method in igraph to compute the dominator tree from a given root node?
### Response:
import igraph as ig

# Create a directed graph
edges = [(0, 1), (1, 2), (2, 3), (0, 3)]
g = ig.Graph(edges=edges, directed=True)

# Select root node
root_vertex_id = 0

# Calculate the dominator tree
# mode 'in' means the 'predecessors' of the dominator tree
# mode 'out' means the 'successors' of the dominator tree
dominator_tree = g.dominator(vid=root_vertex_id, mode='out')

# Print the dominator tree
print(dominator_tree)
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