def d3scan(self, motor1, start1, finish1, motor2, start2, finish2,
               motor3, start3, finish3, npts, dtime):
        self._checkmotors(motor1, motor2, motor3)

        current1 = self.motors[motor1].current()
        start1  += current1
        finish1 += current1

        current2 = self.motors[motor2].current()
        start2  += current2
        finish2 += current2

        current3 = self.motors[motor2].current()
        start3  += current3
        finish3 += current3

        self.a3scan(motor1, start1, finish1,
                    motor2, start2, finish2,
                    motor3, start3, finish3, npts, dtime)
d3scan: relative scan of 3 motors
dataset/ETHPy150Open xraypy/xraylarch/plugins/epics/spyk.py/Spyk.d3scan