moving object forward backward

[Zword]

When the mouse is pointed at the object I want to move it depending on wich key i press. A normal int number works but example +=0.5 does not work.

Code:

cube = vizshape.addCube()

def moveForward():
	object = viz.pick()
	if object.valid():
		pos += 10
		object.setPosition([pos],0,0)
		print 'move backward'

vizact.onkeydown( 'w', moveForward )

def moveBackward ():
	object = viz.pick()
	if object.valid():
		pos += 10
		object.setPosition([pos],0,0)
	print 'move forward'
	
vizact.onkeydown( 's', moveBackward )