docs: def create_folder_structure(project_name, batch_name):
      """This function creates a folder structure for the batch project.
  
      The folder structure consists of main working folder ``project_name`
      located in the ``outdatadir`` (as defined in the cellpy configuration file)
      with a sub-folder named ``batch_name``. It also creates a folder
      inside the ``batch_name`` folder for storing the raw data.
      If the folders does not exist, they will be made. The function also returns
      the name of the info-df.
  
      Args:
          project_name: name of the project
          batch_name: name of the batch
  
      Returns: (info_file, (project_dir, batch_dir, raw_dir))
  
      """
      out_data_dir = prms.Paths["outdatadir"]
      project_dir = os.path.join(out_data_dir, project_name)
      batch_dir = os.path.join(project_dir, batch_name)
      raw_dir = os.path.join(batch_dir, "raw_data")
  
      # create folders
      if not os.path.isdir(project_dir):
          os.mkdir(project_dir)
      if not os.path.isdir(batch_dir):
          os.mkdir(batch_dir)
      if not os.path.isdir(raw_dir):
          os.mkdir(raw_dir)
  
      # create file-name for the info_df (json)
      info_file = "cellpy_batch_%s.json" % batch_name
      info_file = os.path.join(project_dir, info_file)
      return info_file, (project_dir, batch_dir, raw_dir)