class Repository:

''' Always initialize mutable attributes in the constructor '''

def __init__(self):

self.packages = {}

def add_package(self,package):

self.packages[package.name] = package

def remove_package(self,package):

if package.name in self.packages:

del self.packages[package.name]

def total_size(self):

res = 0

for package in self.packages.values():

res+=package.size

return res

class Package:

def __init__(self,name,size):

self.name = name

self.size = size

p1 = Package('src',1024)

p2 = Package('bin',512)

p3 = Package('resource',2044)

r = Repository()

r.add_package(p1)

r.add_package(p2)

r.add_package(p3)

print("Size of Repository After adding three packages in repository : ",r.total_size())

r.remove_package(p3)

print("Size of Repository After removing one packages in repository : ",r.total_size())