class graph:

def __init__(self,gdict=None):

if gdict is None:

gdict = []

self.gdict = gdict

# Get the keys of the dictionary

def getVertices(self):

return list(self.gdict.keys())

# Create the dictionary with graph elements

graph_elements = { "a" : ["b","c"],

"b" : ["a", "d"],

"c" : ["a", "d"],

"d" : ["e"],

"e" : ["d"]

}

g = graph(graph_elements)

print(g.getVertices())