You are given a directed acyclic graph (DAG) represented as an adjacency list. Your task is to return a topological sorting of the graph. If the graph is not a DAG, return an empty list.

``` from collections import defaultdict, deque def topological_sort(graph): indegree = [0] * len(graph) for edges in graph: for dest in edges: indegree[dest] += 1 queue = deque([i for i in range(len(graph)) if indegree[i] == 0]) topo_order = [] while queue: node = queue.popleft() topo_order.append(node) for neighbor in graph[node]: indegree[neighbor] -= 1 if indegree[neighbor] == 0: queue.append(neighbor) return topo_order if len(topo_order) == len(graph) else [] ```