docs: def _key_on_columns(key_on, columns):
          """
          :param key_on: str of column
          :param columns: list of str of columns
          :return: list of str with the key_on in the front of the list
          """
          if key_on is not None:
              if key_on in columns:
                  columns.remove(key_on)
              columns = [key_on] + columns
          return columns