code: def test_pre_transform_planner_warning2():
      # Pre-transform with supported aggregate function should result in no warnings
      vega_spec = standalone_aggregate_spec("mean")
      datasets, warnings = vf.runtime.pre_transform_spec(vega_spec)
      assert len(warnings) == 0
  
      # Pre-transform with unsupported aggregate function should result in one warning
      vega_spec = standalone_aggregate_spec("ci0")
      datasets, warnings = vf.runtime.pre_transform_spec(vega_spec)
      assert len(warnings) == 1
  
      warning = warnings[0]
      assert warning["type"] == "Planner"
      assert "data_0" in warning["message"]
  
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 17 for calling a global function with example usage: test_pre_transform_planner_warning2() without return types