code: def validate_is_non_abstract_vertex_type(self, vertex_classname):
          
          element = self.get_vertex_schema_element_or_raise(vertex_classname)
  
          if element.abstract:
              raise InvalidClassError(u'Expected a non-abstract vertex class, but {} is abstract'
                                      .format(vertex_classname))
docs: Validate that a vertex classname corresponds to a non-abstract vertex class.