love.py

def foo():
  a = []
  b = []
  c = []
  
  def aa():
    # This works
    a.append(1)
    
  def bb():
    # This doesn't
    b += [1]
  
  def cc():
    # This doesn't work either
    c.append(1)
    
    if False:
      c += [2]
  
  aa()
  bb()
  cc()
  
foo()