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    "cme.zm.tick.continuous.2015.parquet",
    "cme.zm.tick.continuous.2016.parquet",
    "cme.zm.tick.continuous.2017.parquet",
    "cme.zm.tick.continuous.2018.parquet",
    "cme.zm.tick.continuous.2019.parquet",
    "cme.zm.tick.continuous.2020.parquet",
    "cme.zm.tick.continuous.2021.parquet",
    "cme.zm.tick.continuous.2022.parquet",
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    "cme.zm.tick.continuous.2024.parquet",
    "cme.zm.tick.continuous.2025.parquet",
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  ],
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      "difference": -2.8000000000000114
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    {
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      "difference": -15.900000000000034
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    {
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      "difference": -2.8000000000000114
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      "difference": -7.0
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    {
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      "decision_session": "2023-07-24",
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      "difference": -16.80000000000001
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    {
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      "difference": -8.599999999999966
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    {
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      "difference": -1.1000000000000227
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    {
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      "difference": -17.30000000000001
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    {
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      "switch_utc": "2023-12-18T23:00:00+00:00",
      "difference": -11.600000000000023
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    {
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      "decision_session": "2024-02-14",
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      "difference": -7.100000000000023
    },
    {
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      "decision_session": "2024-04-16",
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      "switch_utc": "2024-04-16T22:00:00+00:00",
      "difference": 1.099999999999966
    },
    {
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      "switch_utc": "2024-06-24T22:00:00+00:00",
      "difference": -14.699999999999989
    },
    {
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      "switch_utc": "2024-07-23T22:00:00+00:00",
      "difference": -17.5
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    {
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      "decision_session": "2024-08-26",
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      "switch_utc": "2024-08-26T22:00:00+00:00",
      "difference": -5.300000000000011
    },
    {
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      "decision_session": "2024-09-11",
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      "switch_utc": "2024-09-11T22:00:00+00:00",
      "difference": 4.0
    },
    {
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      "to_contract": "ZMF25-CBOT",
      "decision_session": "2024-11-19",
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      "switch_utc": "2024-11-19T23:00:00+00:00",
      "difference": 1.6999999999999886
    },
    {
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      "to_contract": "ZMH25-CBOT",
      "decision_session": "2024-12-17",
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      "switch_utc": "2024-12-17T23:00:00+00:00",
      "difference": 6.2999999999999545
    },
    {
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      "to_contract": "ZMK25-CBOT",
      "decision_session": "2025-02-19",
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      "switch_utc": "2025-02-19T23:00:00+00:00",
      "difference": 8.300000000000011
    },
    {
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      "to_contract": "ZMN25-CBOT",
      "decision_session": "2025-04-16",
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      "switch_utc": "2025-04-16T22:00:00+00:00",
      "difference": 7.300000000000011
    },
    {
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      "to_contract": "ZMQ25-CBOT",
      "decision_session": "2025-06-24",
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      "switch_utc": "2025-06-24T22:00:00+00:00",
      "difference": 4.199999999999989
    },
    {
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      "to_contract": "ZMU25-CBOT",
      "decision_session": "2025-07-21",
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      "switch_utc": "2025-07-21T22:00:00+00:00",
      "difference": 4.300000000000011
    },
    {
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      "to_contract": "ZMV25-CBOT",
      "decision_session": "2025-08-25",
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      "new_volume": 15849,
      "switch_utc": "2025-08-25T22:00:00+00:00",
      "difference": -6.0
    },
    {
      "from_contract": "ZMV25-CBOT",
      "to_contract": "ZMZ25-CBOT",
      "decision_session": "2025-09-10",
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      "new_volume": 38975,
      "switch_utc": "2025-09-10T22:00:00+00:00",
      "difference": 2.400000000000034
    },
    {
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      "to_contract": "ZMF26-CBOT",
      "decision_session": "2025-11-18",
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      "new_volume": 35010,
      "switch_utc": "2025-11-18T23:00:00+00:00",
      "difference": 1.8000000000000114
    },
    {
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      "to_contract": "ZMH26-CBOT",
      "decision_session": "2025-12-16",
      "old_volume": 25982,
      "new_volume": 28202,
      "switch_utc": "2025-12-16T23:00:00+00:00",
      "difference": 3.6999999999999886
    },
    {
      "from_contract": "ZMH26-CBOT",
      "to_contract": "ZMK26-CBOT",
      "decision_session": "2026-02-18",
      "old_volume": 25746,
      "new_volume": 31259,
      "switch_utc": "2026-02-18T23:00:00+00:00",
      "difference": 4.600000000000023
    },
    {
      "from_contract": "ZMK26-CBOT",
      "to_contract": "ZMN26-CBOT",
      "decision_session": "2026-04-15",
      "old_volume": 33557,
      "new_volume": 34961,
      "switch_utc": "2026-04-15T22:00:00+00:00",
      "difference": -3.5
    },
    {
      "from_contract": "ZMN26-CBOT",
      "to_contract": "ZMQ26-CBOT",
      "decision_session": "2026-06-24",
      "old_volume": 13277,
      "new_volume": 15330,
      "switch_utc": "2026-06-24T22:00:00+00:00",
      "difference": -1.5
    },
    {
      "from_contract": "ZMQ26-CBOT",
      "to_contract": "ZMU26-CBOT",
      "decision_session": "2026-07-27",
      "old_volume": 15674,
      "new_volume": 17276,
      "switch_utc": "2026-07-27T22:00:00+00:00",
      "difference": -0.6999999999999886
    },
    {
      "from_contract": "ZMU26-CBOT",
      "to_contract": "ZMV26-CBOT",
      "decision_session": "2026-08-25",
      "old_volume": 8132,
      "new_volume": 10846,
      "switch_utc": "2026-08-25T22:00:00+00:00",
      "difference": 3.3999999999999773
    },
    {
      "from_contract": "ZMV26-CBOT",
      "to_contract": "ZMZ26-CBOT",
      "decision_session": "2026-09-14",
      "old_volume": 13217,
      "new_volume": 45462,
      "switch_utc": "2026-09-14T22:00:00+00:00",
      "difference": 6.0
    }
  ]
}