docs: def get_selected_elements_of_core_class(self, core_element_type):
          """Returns all selected elements having the specified `core_element_type` as state element class
  
          :return: Subset of the selection, only containing elements having `core_element_type` as state element class
          :rtype: set
          """
          if core_element_type is Outcome:
              return self.outcomes
          elif core_element_type is InputDataPort:
              return self.input_data_ports
          elif core_element_type is OutputDataPort:
              return self.output_data_ports
          elif core_element_type is ScopedVariable:
              return self.scoped_variables
          elif core_element_type is Transition:
              return self.transitions
          elif core_element_type is DataFlow:
              return self.data_flows
          elif core_element_type is State:
              return self.states
          raise RuntimeError("Invalid core element type: " + core_element_type)