<｜begin▁of▁sentence｜>### Instruction:
Given a directed graph with vertices [0, 1, 2, 3, 4] and edges [(0, 1), (1, 2), (2, 3), (3, 4)], can you use the is_tree function in igraph to check if the graph is an outward oriented tree?
### Response:
import igraph as ig

# Create a directed graph example
g = ig.Graph(directed=True)
g.add_vertices(5)
g.add_edges([(0, 1), (1, 2), (2, 3), (3, 4)])

# Check if the graph is a tree
is_a_tree = g.is_tree(mode='out')
print('Is the graph a tree?:', is_a_tree)
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