docs: def _match_dfs_expr(lo_meta, expr, tt):
      """
      Use the given expression to get all data frames that match the criteria (i.e. "paleo measurement tables")
      :param dict lo_meta: Lipd object metadata
      :param str expr: Search expression
      :param str tt: Table type (chron or paleo)
      :return list: All filenames that match the expression
      """
      logger_dataframes.info("enter match_dfs_expr")
      filenames = []
      s = "{}Data".format(tt)
  
      # Top table level. Going through all tables of certain type (i.e. chron or paleo)
      for k, v in lo_meta["{}Data".format(tt)].items():
  
          # Inner table level. Get data from one specific table
          if "measurement" in expr:
              for k1, v1 in v["{}MeasurementTable".format(tt)].items():
                  try:
                      f = v1["filename"]
                      if f.endswith(".csv"):
                          filenames.append(f)
                  except KeyError:
                      # Not concerned if the key wasn't found.
                      logger_dataframes.info("match_dfs_expr: KeyError: filename not found in: {} {}".format(tt, "measurement"))
  
          elif "ensemble" in expr:
              for k1, v1 in v["{}Model".format(tt)].items():
                  try:
                      f = v1["ensembleTable"]["filename"]
                      if f.endswith(".csv"):
                          filenames.append(f)
                  except KeyError:
                      # Not concerned if the key wasn't found.
                      logger_dataframes.info("match_dfs_expr: KeyError: filename not found in: {} {}".format(tt, "ensemble"))
  
          elif "model" in expr:
              for k1, v1 in v["{}Model".format(tt)].items():
                  try:
                      f = v1["{}ModelTable".format(tt)]["filename"]
                      if f.endswith(".csv"):
                          filenames.append(f)
                  except KeyError:
                      # Not concerned if the key wasn't found.
                      logger_dataframes.info("match_dfs_expr: KeyError: filename not found in: {} {}".format(tt, "model"))
  
          elif "dist" in expr:
              for k1, v1 in v["{}Model".format(tt)].items():
                  for k2, v2 in v1["distribution"].items():
                      try:
                          f = v2["filename"]
                          if f.endswith(".csv"):
                              filenames.append(f)
                      except KeyError:
                          # Not concerned if the key wasn't found.
                          logger_dataframes.info(
                              "match_dfs_expr: KeyError: filename not found in: {} {}".format(tt, "dist"))
  
      logger_dataframes.info("exit match_dfs_expr")
      return filenames