On Dec 22, 2009, at 12:31, Floris van Manen wrote: class OpEnAf: def __init__(self, v) self.v = v def erbij(self, x): self.v += x def eraf(self, x): self.v -= x def show(self): print 'Tussenstand:', self.v a = OpEnAf( 10 ) a.show() a.erbij(100) a.show() a.eraf(20) a.show() for i in range(10): a.erbij(i) print i, 'erbij is', a.v a.show()