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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_edge(self, a, b):
 """Used to add edges to the graph. 'a' and 'b' are vertexes and if 'a' or 'b' doesn't exisit then the vertex is created Args: a (hash):
 is one vertex of the edge b (hash):
 is another vertext of the edge """

        neighbors_of_a = self.adjacency_lists.get(a)
        if not neighbors_of_a:
            neighbors_of_a = set()
            self.adjacency_lists[a] = neighbors_of_a

        neighbors_of_a.add(b)

        neighbors_of_b = self.adjacency_lists.get(b)
        if not neighbors_of_b:
            neighbors_of_b = set()
            self.adjacency_lists[b] = neighbors_of_b

        neighbors_of_b.add(a)