python中的错误处理

def foo():
  r = some_function()
  if r==(-1):
    return (-1)
  # do something
  return r

def bar():
  r = foo()
  if r==(-1):
    print 'Error'
  else:
    pass

try:
  print 'try...'
  r = 10 / 0
  print 'result:', r
except ZeroDivisionError, e:
  print 'except:', e
finally:
  print 'finally...'
print 'END'