Looping around a simple list of tuples

[Martin d'Anjou]

I have a list of tuples, each tuple is a (scalar , list)

a=[("r1",[1,2,3]),("r2",[8,9,10]),("r5",[12,14,16])]

for el in a:
    print el
    for r,l in el:
       print "R "+`r`
       print "L "+`l`

('r1', [1, 2, 3])
R 'r'
L '1'
Traceback (innermost last):
   File "<stdin>", line 3, in ?
ValueError: unpack list of wrong size

In my mind, the 'el' implicit variable is a tuple, and the for r,l loop should 
just work but it does not. How come?

Thanks,
Martin