docs: def _add(self, column):
          """
          :param column: ANY COLUMN OBJECT
          :return:  None IF column IS canonical ALREADY (NET-ZERO EFFECT)
          """
          columns_for_table = self.data.setdefault(column.es_index, {})
          existing_columns = columns_for_table.setdefault(column.name, [])
  
          for canonical in existing_columns:
              if canonical is column:
                  return None
              if canonical.es_type == column.es_type:
                  if column.last_updated > canonical.last_updated:
                      for key in Column.__slots__:
                          old_value = canonical[key]
                          new_value = column[key]
                          if new_value == None:
                              pass  # DO NOT BOTHER CLEARING OLD VALUES (LIKE cardinality AND paritiions)
                          elif new_value == old_value:
                              pass  # NO NEED TO UPDATE WHEN NO CHANGE MADE (COMMON CASE)
                          else:
                              canonical[key] = new_value
                  return canonical
          existing_columns.append(column)
          return column