codefun.py

a=[(2010,2),(2009,4),(1989,8),(2009,7)]

new_dict={}

for i in a:
    if i[0] not in new_dict:
        new_dict[i[0]]=[i[1]]
    else:

        try:
            new_dict[i[0]].append(i[1])

        except KeyError:
            pass

print(new_dict)



#output 

{2009: [4, 7], 2010: [2], 1989: [8]}