<｜begin▁of▁sentence｜>### Instruction:
As an illustrator creating visual artwork for a publication, imagine that you are given a graph representing a network of connections between different points of interest in a city. Each edge in the graph is associated with a 'weight' that represents the distance between the points it connects, with some edges having a 'None' value due to incomplete information. Now, you are tasked with using the 'is_weighted' function in your preferred graph library to determine whether the graph represents a weighted network, considering the presence of the 'weight' edge attribute.
### Response:
from igraph import Graph

# Create a graph with weights on some edges
g = Graph(edges=[(0, 1), (1, 2), (2, 3)])
g.es['weight'] = [1.0, 2.0, None]

# Determine if the graph is weighted
is_weighted = g.is_weighted()

# Print whether the graph is weighted or not
print('Graph is weighted:' if is_weighted else 'Graph is not weighted')
<|EOT|>
