code: def test_from_date():
      df = conversion_data()
      data_id, column_type = "1", "type_conversion"
      i = 0
      build_data_inst({data_id: df})
  
      cfg = {
          "col": "date",
          "to": "str",
          "from": "datetime64",
          "fmt": "%m/%d/%Y",
      }
      builder = ColumnBuilder(
          data_id, column_type, "Col{}".format(++i), cfg
      )
      verify_builder(builder, lambda col: col.values[0] == "01/01/2020")
  
      cfg = {
          "col": "date",
          "to": "int",
          "from": "datetime64",
          "unit": "YYYYMMDD",
      }
      builder = ColumnBuilder(
          data_id, column_type, "Col{}".format(++i), cfg
      )
      verify_builder(builder, lambda col: col.values[0] == 20200101)
  
      cfg = {
          "col": "date",
          "to": "int",
          "from": "datetime64",
          "unit": "ms",
      }
      builder = ColumnBuilder(
          data_id, column_type, "Col{}".format(++i), cfg
      )
      # this fails due to local machine timezone. The time here is "Jan 01 2020 05:00:00 GMT+0000"
      verify_builder(builder, lambda col: col.values[0] == 1577854800)
  
file_path: dtale/tests/dtale/column_builders/test_type_conversion.py
imports: import numpy
  import pandas
  import pytest
  from dtale.column_builders import ColumnBuilder
  from tests.dtale.column_builders.test_column_builders import verify_builder
  from tests.dtale import build_data_inst
label_desc: Use image node_id 6 for calling a global function with example usage: test_from_date() without return types