code: def _proc_group(self, style, adopt=True):
          
          fields = self.fields
          if style is not None:
              if adopt:
                  style = elements.adopt(self.style, style)
              elements.validate(style)
  
              for column in self.columns:
                  fields[column].add(
                      "pre", "override",
                      *(self.procgen.pre_from_style(style[column])))
                  fields[column].add(
                      "post", "override",
                      *(self.procgen.post_from_style(style[column])))
              return "override"
          else:
              return "default"
docs: Return whether group is "default" or "override".
  
          In the case of "override", the self.fields pre-format and post-format
          processors will be set under the "override" key.
  
          Parameters
          ----------
          style : dict
              A style that follows the schema defined in pyout.elements.
          adopt : bool, optional
              Merge `self.style` and `style`, giving priority to the latter's
              keys when there are conflicts.  If False, treat `style` as a
              standalone style.