docs: def inject(self, raw_data, row_change_callback=None):
          """ Use this function to add rows or update existing rows in the
          spreadsheet.
      
          Args: 
            raw_data (dict): A dictionary of dictionaries. Where the keys of the
               outer dictionary uniquely identify each row of data, and the inner
               dictionaries represent the field,value pairs for a row of data.
     
            row_change_callback (Optional) (func): A callback function that you
               can use to track changes to rows on the spreadsheet. The
               row_change_callback function must take four parameters like so:
  
               change_callback(row_key, 
                               row_dict_before, 
                               row_dict_after, 
                               list_of_changed_keys)
  
          Returns:
            UpdateResults (object): A simple counter object providing statistics
              about the changes made by sheetsync.
          """
          return self._update(raw_data, row_change_callback, delete_rows=False)