<｜begin▁of▁sentence｜>### Instruction:
Given a graph with the edge set [(1, 2), (2, 3), (3, 4), (4, 1)], determine whether the graph is a regular graph using the is_regular function from NetworkX.
### Response:
import networkx as nx

G = nx.DiGraph([(1, 2), (2, 3), (3, 4), (4, 1)])
regular = nx.is_regular(G)
print('Is the graph regular:', regular)
<|EOT|>
