code: def build_props(self):
          
          props = {}
          if self.filters:
              props["filters"] = {}
              for grp in self.filters:
                  props["filters"][grp] = [f.params for f in self.filters[grp]]
          if self.charts:
              props["charts"] = [c.params for c in self.charts]
  
          props["type"] = self.layout
          return props
docs: Build the props dictionary.