code: def test_pep8_bis():
      text = """# This is a markdown cell
  
  # a code cell
  def f(x):
      return x + 1
  
  # And another markdown cell
  # Separated from f by just one line
  # As there is no code here
  """
      nb = reads(text, "py")
      for cell in nb.cells:
          assert not cell.metadata
  
      text2 = writes(nb, "py")
      compare(text2, text)
  
file_path: jupytext/tests/unit/test_pep8.py
imports: from nbformat.v4.nbbase import new_code_cell, new_notebook
  from jupytext import read, reads, writes
  from jupytext.compare import compare
  from jupytext.pep8 import cell_ends_with_code, cell_ends_with_function_or_class, cell_has_code, next_instruction_is_function_or_class, pep8_lines_between_cells
label_desc: Use image node_id 8 for calling a global function with example usage: test_pep8_bis() without return types