code: def test_pre_transform_multi_partition():
      n = 4050
      order_items = pd.DataFrame({"menu_item": [0] * n + [1] * n})
  
      vega_spec = order_items_spec()
      new_spec, warnings = vf.runtime.pre_transform_spec(
          vega_spec,
          inline_datasets={
              "order_items": order_items,
          },
      )
  
      assert new_spec["data"][1] == dict(
          name="data_0",
          values=[
              {"menu_item": 0, "__count": n},
              {"menu_item": 1, "__count": n},
          ],
      )
  
imports: import pandas
  import pytest
  from pandas import Timestamp, NaT
  import pyarrow
  import vegafusion
  import json
  import polars
  from datetime import date
  import decimal
  import base64
label_desc: Use image node_id 13 for calling a global function with example usage: test_pre_transform_multi_partition() without return types