Building an undirected graph and finding shortest path using Dictionaries in Python

# Python3 implementation to build a 
# graph using Dictionaries

from collections import defaultdict

# Function to build the graph
def build_graph():
    edges = [
        ["A", "B"], ["A", "E"], 
        ["A", "C"], ["B", "D"],
        ["B", "E"], ["C", "F"],
        ["C", "G"], ["D", "E"]
    ]
    graph = defaultdict(list)
    
    # Loop to iterate over every 
    # edge of the graph
    for edge in edges:
        a, b = edge[0], edge[1]
        
        # Creating the graph 
        # as adjacency list
        graph[a].append(b)
        graph[b].append(a)
    return graph

if __name__ == "__main__":
    graph = build_graph()
    
    print(graph)

# Python implementation to find the 
# shortest path in the graph using 
# dictionaries 

# Function to find the shortest
# path between two nodes of a graph
def BFS_SP(graph, start, goal):
    explored = []
    
    # Queue for traversing the 
    # graph in the BFS
    queue = [[start]]
    
    # If the desired node is 
    # reached
    if start == goal:
        print("Same Node")
        return
    
    # Loop to traverse the graph 
    # with the help of the queue
    while queue:
        path = queue.pop(0)
        node = path[-1]
        
        # Condition to check if the
        # current node is not visited
        if node not in explored:
            neighbours = graph[node]
            
            # Loop to iterate over the 
            # neighbours of the node
            for neighbour in neighbours:
                new_path = list(path)
                new_path.append(neighbour)
                queue.append(new_path)
                
                # Condition to check if the 
                # neighbour node is the goal
                if neighbour == goal:
                    print("Shortest path = ", *new_path)
                    return
            explored.append(node)

    # Condition when the nodes 
    # are not connected
    print("So sorry, but a connecting"\
                "path doesn't exist :(")
    return

# Driver Code
if __name__ == "__main__":
    
    # Graph using dictionaries
    graph = {'A': ['B', 'E', 'C'],
            'B': ['A', 'D', 'E'],
            'C': ['A', 'F', 'G'],
            'D': ['B', 'E'],
            'E': ['A', 'B', 'D'],
            'F': ['C'],
            'G': ['C']}
    
    # Function Call
    BFS_SP(graph, 'A', 'D')