Define a function breadthFirst, which performs a breadth-first traversal on a graph, given a start vertex. This function should return a list of the labels of the vertices in the order in which they are visited. Test the function thoroughly with the case study program.(In Python with comments) Use this template: class Vertex:     def __init__(self, label):         self.label = label         self.neighbors = []     def __str__(self):         return self.label          def add_neighbor(self, neighbor):         self.neighbors.append(neighbor)         self.neighbors.sort() # Graph definition provided, please don't modify any of the provided code # Add any helper methods if necessary class Graph:     def __init__(self):         self.vertices = []     # Add a vertex object      def add_vertex(self, vertex):         self.vertices.append(vertex)     # Get index of a vertex with corresponding label     # Return -1 if not found     def get_vertex_index(self, label):         index = 0         for vertex in self.vertices:             if label == str(vertex):

Define a function breadthFirst, which performs a breadth-first traversal on a graph, given a start vertex. This function should return a list of the labels of the vertices in the order in which they are visited. Test the function thoroughly with the case study program.(In Python with comments)

Use this template:

class Vertex:
    def __init__(self, label):
        self.label = label
        self.neighbors = []

    def __str__(self):
        return self.label
    
    def add_neighbor(self, neighbor):
        self.neighbors.append(neighbor)
        self.neighbors.sort()

# Graph definition provided, please don't modify any of the provided code
# Add any helper methods if necessary
class Graph:
    def __init__(self):
        self.vertices = []

    # Add a vertex object 
    def add_vertex(self, vertex):
        self.vertices.append(vertex)

    # Get index of a vertex with corresponding label
    # Return -1 if not found
    def get_vertex_index(self, label):
        index = 0
        for vertex in self.vertices:
            if label == str(vertex):
                return index
            index += 1
        return -1

    # Find a vertex with corresponding label and return as Vertex object
    def find_vertex(self, label):
        for vertex in self.vertices:
            if label == str(vertex):
                return vertex
        return None
    
    # Add an edge from a vertex with from_label to a vertex with to_label
    # These vertices must already exist in the graph
    def add_edge(self, from_label, to_label):
        source_vertex = self.find_vertex(from_label)
        dest_vertex = self.find_vertex(to_label)
        if source_vertex is not None and dest_vertex is not None:
            source_vertex.add_neighbor(to_label)

# Perform breadth-first search on a directed graph g starting at vertex with label start_label
# Return a list of vertices' name in the order in which they are visited
# Remove the "pass" statement and implement the function
def breadthFirst(g, start_label):
    pass

if __name__ == "__main__":
    # TODO: (Optional) your test code here
    my_graph = Graph()
    vertices = ["0", "1", "2", "3", "4", "5"]
    edges = [["0", "1"], ["0", "2"], ["1", "3"], ["1", "4"], ["2", "5"]]

    for vertex in vertices:
        my_graph.add_vertex(Vertex(vertex))

    for edge in edges:
        my_graph.add_edge(edge[0], edge[1])

    for vertex in my_graph.vertices: # Print out adjacency list
        print("Vertex " , vertex, ":", vertex.neighbors)

    print(breadthFirst(my_graph, "0")) # Correct Output: ["0","1","2","3","4","5"]