docs: def _generate_header(notebook_object, notebook_type, notebook_file):
      """
      Internal function that is used for generation of the notebooks footer.
  
      ----------
      Parameters
      ----------
      notebook_object : notebook object
          Object of "notebook" class where the header will be created.
  
      notebook_file : str
          Notebook filename.
  
      notebook_type : str
          Notebook type: - "Main_Files_Signal_Samples"
                         - "Main_Files_By_Category"
                         - "Main_Files_By_Difficulty"
                         - "Main_Files_By_Tag"
                         - "Acquire"
                         - "Open"
                         - "Visualise"
                         - "Process"
                         - "Detect"
                         - "Extract"
                         - "Decide"
                         - "Explain"
  
      """
  
      header_aux = HEADER
      header_aux = header_aux.replace("FILENAME", notebook_file.split(".")[0] + ".dwipynb")
      header_aux = header_aux.replace("SOURCE", "https://mybinder.org/v2/gh/biosignalsnotebooks/biosignalsnotebooks/master?filepath=header_footer%2Fbiosignalsnotebooks_environment%2Fcategories%2F" + notebook_type + "%2F" + notebook_file + ".dwipynb")
  
      if "Main_Files" in notebook_type:
          header_aux = header_aux.replace("../MainFiles/", "")
  
      # ================ Insertion of the div reserved to the Notebook Description ===================
      notebook_object["cells"].append(nb.v4.new_markdown_cell(header_aux,
                                                              **{"metadata":
                                                                 {"tags": ["header"]}}))