code: def set_xtick_labels_for_all(self, row_column_list=None, labels=None):
          
          if row_column_list is None:
              for subplot in self.subplots:
                  self.set_xtick_labels(subplot.row, subplot.column, labels)
          else:
              for row, column in row_column_list:
                  self.set_xtick_labels(row, column, labels)
docs: Manually specify the x-axis tick labels.
  
          :param row_column_list: a list containing (row, column) tuples to
              specify the subplots, or None to indicate *all* subplots.
          :type row_column_list: list or None
          :param labels: list of tick labels.