code: def date_column_spec():
      return json.loads(
          r"""
  {
    "$schema": "https://vega.github.io/schema/vega/v5.json",
    "description": "A scatterplot showing horsepower and miles per gallons for various cars.",
    "background": "white",
    "padding": 5,
    "width": 400,
    "height": 20,
    "style": "cell",
    "data": [
      {
        "name": "data_0",
        "url": "vegafusion+dataset://dates",
        "transform": [
          {
            "type": "formula",
            "expr": "toDate(datum[\"date_col\"])",
            "as": "date_col"
          }
        ]
      }
    ],
    "marks": [
      {
        "name": "marks",
        "type": "symbol",
        "style": ["point"],
        "from": {"data": "data_0"},
        "encode": {
          "update": {
            "opacity": {"value": 0.7},
            "fill": {"value": "transparent"},
            "stroke": {"value": "#4c78a8"},
            "ariaRoleDescription": {"value": "point"},
            "description": {
              "signal": "\"date32: \" + (timeFormat(datum[\"date32\"], '%b %d, %Y'))"
            },
            "x": {"scale": "x", "field": "date_col"},
            "y": {"signal": "height", "mult": 0.5}
          }
        }
      }
    ],
    "scales": [
      {
        "name": "x",
        "type": "time",
        "domain": {"data": "data_0", "field": "date_col"},
        "range": [0, {"signal": "width"}]
      }
    ]
  }
  """
      )
  
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 6 for calling a global function with example usage: date_column_spec() and returns: json