do topo sort in python

main.py
from collections import defaultdict

def topo_sort(graph):
    in_degree = {node: 0 for node in graph}
    for node in graph:
        for neighbor in graph[node]:
            in_degree[neighbor] += 1
    
    queue = [node for node in in_degree if in_degree[node] == 0]
    result = []
    
    while queue:
        node = queue.pop(0)
        result.append(node)
        
        for neighbor in graph[node]:
            in_degree[neighbor] -= 1
            if in_degree[neighbor] == 0:
                queue.append(neighbor)
    
    if len(result) == len(graph):
        return result
    else:
        return []  # Cycle detected in the graph

# Example usage
graph = {
    'A': ['B', 'C'],
    'B': ['D'],
    'C': ['D'],
    'D': []
}

print(topo_sort(graph))
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