code: def test_identity_source_write_read(ipynb_py_R_jl_file):
      """Test that writing the notebook with rmd, and read again,
      is the same as removing outputs"""
  
      with open(ipynb_py_R_jl_file) as fp:
          nb1 = nbformat.read(fp, as_version=4)
  
      rmd = jupytext.writes(nb1, "Rmd")
      nb2 = jupytext.reads(rmd, "Rmd")
  
      compare_notebooks(nb2, nb1, "Rmd")
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_identity_source_write_read(ipynb_py_R_jl_file) without return types