<｜begin▁of▁sentence｜>### Instruction:
As a marriage counselor, I often use the analogy of a network of communication between partners. Just like in a directed graph where information flows from one node to another, in a relationship, communication flows from one partner to the other. Now, let's say there's a couple where Partner A communicates with Partner B, who in turn communicates with Partner C, and finally, Partner C communicates back with Partner A. This represents a healthy flow of communication with no loops, similar to a Directed Acyclic Graph (DAG). However, if a loop is introduced, where Partner C starts communicating back with Partner A creating a cycle, it can disrupt the healthy flow of communication and cause issues within the relationship. Using this analogy, we can discuss how introducing a cycle in the communication network affects the relationship dynamics.
### Response:
from igraph import Graph

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

# Add a cycle to create a graph that is not a DAG
#g.add_edges([(3, 0)])

# Check if the graph is a DAG
is_dag = g.is_dag()

# Output the result
print('The graph is a DAG:', is_dag)
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