docs: def _get_header_keys(row):
      """
      Get the variable header keys from this special row
      :return list: Header keys
      """
      # Swap out NOAA keys for LiPD keys
      for idx, key in enumerate(row):
          key_low = key.value.lower()
  
          # Simple case: Nothing fancy here, just map to the LiPD key counterpart.
          if key_low in EXCEL_LIPD_MAP_FLAT:
              row[idx] = EXCEL_LIPD_MAP_FLAT[key_low]
  
          # Nested data case: Check if this is a calibration, interpretation, or some other data that needs to be nested.
          # elif key_low:
          #     pass
  
          # Unknown key case: Store the key as-is because we don't have a LiPD mapping for it.
          else:
              try:
                  row[idx] = key.value
              except AttributeError as e:
                  logger_excel.warn("excel_main: get_header_keys: unknown header key, unable to add: {}".format(e))
  
      # Since we took a whole row of cells, we have to drop off the empty cells at the end of the row.
      header_keys = _rm_cells_reverse(row)
      return header_keys