friends = {
    'Ross' : {
        'Last Name' : 'Geller',
        'Birth year': '1968'
    },
    'Joey' : {
        'Last Name' : 'Tribiani',
        'Birth Year': '1975'
    },
    'Chandler' : {
        'Last Name' : 'Bing',
        'Birth Year': '1969'
    }
}

print(friends)

x = dict(Last_Name='Green',Birth_Year='1973')
y = dict(Last_Name='Geller',Birth_Year='1970')
z = dict(Last_Name='Buffay',Birth_Year='1968')

friendss = {
    'Rachel':x,
    'Monica':y,
    'Pheboe':z
}

print(friendss)