syntax glitch with +=

[David Eppstein]

If L and M are lists, L += M is the same as L.extend(M), right?
Nope:

L=[]

def test1():
   print L
   L.extend([1,2])

def test2():
   print L
   L += [3,4]

One of these two works, the other produces an error.
Surprised me when I encountered it, anyway...

-- 
David Eppstein       UC Irvine Dept. of Information & Computer Science
eppstein at ics.uci.edu http://www.ics.uci.edu/~eppstein/