code: def test_split_at_heading_in_metadata(
      markdown="""---
  jupyter:
    jupytext:
      split_at_heading: true
  ---
  
  A paragraph
  
  # H1 Header
  """,
      nb_expected=new_notebook(
          cells=[
              new_markdown_cell("A paragraph"),
              new_markdown_cell("# H1 Header"),
          ]
      ),
  ):
      nb = jupytext.reads(markdown, ".md")
      compare_notebooks(nb, nb_expected)
  
imports: from nbformat.v4.nbbase import new_code_cell, new_markdown_cell, new_notebook, new_raw_cell
  import jupytext
  from jupytext.combine import combine_inputs_with_outputs
  from jupytext.compare import compare, compare_cells, compare_notebooks
label_desc: Use image node_id 8 for calling a global function with example usage: test_split_at_heading_in_metadata(markdown, nb_expected) without return types