code: def merge_stats(self, other_col_counters):
          
          for column_name, _ in self._column_stats.items():
              self._column_stats[column_name] = self._column_stats[column_name] \
                  .mergeStats(other_col_counters._column_stats[column_name])
          return self
docs: Merge statistics from a different column stats counter in to this one.
          Parameters
          ----------
          other_column_counters: Other col_stat_counter to marge in to this one.