def dft(self, starting_vertex):
"""
Print each vertex in depth-first order
beginning from starting_vertex.
"""
q = Stack()
self.visited = {starting_vertex}
q.push(starting_vertex)
while len(q) != 0:
node = q.pop()
print(node)
to_visit: set = self.get_neighbors(node)
q.multi_push(to_visit)
self.visited = self.visited.union(to_visit)
self.visited = set()
print()
