removed exists from bool argument
removed exists from bool argument

FCP-INDI/nipype,carolFrohlich/nipype,mick-d/nipype,FCP-INDI/nipype,carolFrohlich/nipype,carolFrohlich/nipype,mick-d/nipype,FCP-INDI/nipype,mick-d/nipype,FCP-INDI/nipype,carolFrohlich/nipype,mick-d/nipype