code: def test_layout_simple() -> None:
      p1, p2, p3, p4 = figure(), figure(), figure(), figure()
  
      grid = layout([[p1, p2], [p3, p4]], sizing_mode="fixed")
  
      assert isinstance(grid, Column)
      for r in grid.children:
          assert isinstance(r, Row)
  
file_path: bokeh/tests/unit/bokeh/test_layouts.py
imports: from __future__ import annotations
  import pytest
  from unittest import mock
  from bokeh.core.validation import check_integrity, process_validation_issues
  from bokeh.layouts import column, grid, gridplot, group_tools, layout, row
  from bokeh.models import BoxAnnotation, BoxSelectTool, Column, GlyphRenderer, GridBox, GridPlot, HoverTool, LayoutDOM, PanTool, Row, SaveTool, Spacer, TapTool, ToolProxy
  from bokeh.plotting import figure
label_desc: Use image node_id 7 for calling a global function with example usage: test_layout_simple() without return types