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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def save_tip_length(labware: Labware, length: float):
 """ Function to be used whenever an updated tip length is found for of a given tip rack. If an offset file does not exist, create the file using labware id as the filename. If the file does exist, load it and modify the length and the lastModified fields under the "tipLength" key. """

    calibration_path = CONFIG['labware_calibration_offsets_dir_v4']
    if not calibration_path.exists():
        calibration_path.mkdir(parents=True, exist_ok=True)
    labware_offset_path = calibration_path/'{}.json'.format(labware._id)
    calibration_data = _helper_tip_length_data_format(
        str(labware_offset_path), length)
    with labware_offset_path.open('w') as f:
        json.dump(calibration_data, f)
    labware.tip_length = length