It seems there is a simpler solution that the one provided. Why so much complexity?

```
from collections import deque
class Vertex:
children = []
def __init__(self, value):
self.value = value
def topological_sort(vertices, edges):
sortedOrder = []
vertices = [None for _ in range(vertices)]
for parent, child in edges:
if vertices[parent] is None:
vertices[parent] = Vertex(parent)
if vertices[child] is None:
vertices[child] = Vertex(child)
vertices[parent].children.append(vertices[child])
queue = deque()
queue.append(vertices[-1])
seen = {}
while queue:
vertex = queue.popleft()
sortedOrder.append(vertex.value)
for child in vertex.children:
if child.value not in seen:
seen[child.value] = True
queue.append(child)
return sortedOrder
```

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