def METHOD_NAME(self, plc = 10):  # number of power line cycles, default is 10
    plc = float(plc)
    if (plc != 100) and (plc != 10) and (plc != 1) and (plc != 0.2) and (plc != 0.02):
        print >> sys.stderr, "HP_34401A: NPLC can only be 1, 10 or 100"
        return -1
    mode = self.get_measurement_mode()
    if (mode != "CURR") and (mode != "VOLT"):
        print >> sys.stderr, "HP_34401A: NPLC not defined"
        return -1
    com_str = "%s:NPLCycles %f" % (mode, plc)
    self._visainstrument.write(com_str)
    sleep(0.05)
    return self.get_NPLC()