<｜begin▁of▁sentence｜>### Instruction:
As a Quality Assurance (QA) Analyst, you're tasked with assessing, testing, and evaluating various components to ensure they meet quality standards. Suppose you're working in a technology company where you're responsible for testing the functionality of a navigation system. You receive a task to verify the shortest route calculation feature from a source location (ID 0) to a destination (ID 5) using a directed graph representation, which can be imported from a file named 'graph.gml'. To accomplish this, you decide to employ the A-Star algorithm, leveraging its ability to find the most efficient path based on heuristic evaluations.
### Response:
from igraph import Graph

# Create a graph instance (assuming Graph is from the igraph package)
g = Graph.Read_GML('graph.gml')

# Define a heuristic function
# For instance, a dummy heuristic function that always returns zero
heuristic = lambda graph, vertex1, vertex2: 0

# Calculate the shortest path from source to target using A* algorithm
# Replace 'source' and 'target' with the appropriate vertex IDs
path = g.get_shortest_paths_astar(source=0, target=5, heuristic_func=heuristic, weights=None)

# Print out the path
print('Shortest path (A*):', path)
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