def _set_flow_rate(pipette, params) -> None:
    """
    Set flow rate in uL/mm, to value obtained from command's params.
    """
    flow_rate_param = params['flowRate']

    if not (flow_rate_param > 0):
        raise RuntimeError('Positive flowRate param required')

    pipette.flow_rate = {
        'aspirate': flow_rate_param,
        'dispense': flow_rate_param
    }