code: def add_factuality(self,my_fact):
          
          if self.factuality_layer is None:
              self.factuality_layer = Cfactualities()
              self.root.append(self.factuality_layer.get_node())
          self.factuality_layer.add_factuality(my_fact)
docs: Adds a factuality to the factuality layer
          @type my_fact: L{Cfactuality}
          @param my_fact: factuality object