Python: extend items in a list

I am trying to create a new list based on the old one, from ['a', 'b', 'c'] to ['a12', 'b12', 'c12'].

the classic way could be:

a = ['a','b','c']
aa = []

for item in a:
    aa.append(item + '12')

print aa

      

        
        
        
      

    

however I want to know the best way so that I try:

aa = a.extend('12%s' % item for item in l[:])

      

        
        
        
      

    

and

aa = [item.join('12') for item in l]

      

        
        
        
      

    

but they do not give the most correct one. What are the best ways?

thank.