code: def validate(self):
          
          if not isinstance(self.direction, six.string_types):
              raise TypeError(u'Expected string direction, got: {} {}'.format(
                  type(self.direction).__name__, self.direction))
  
          validate_edge_direction(self.direction)
          validate_safe_string(self.edge_name)
  
          if not isinstance(self.optional, bool):
              raise TypeError(u'Expected bool optional, got: {} {}'.format(
                  type(self.optional).__name__, self.optional))
  
          if not isinstance(self.within_optional_scope, bool):
              raise TypeError(u'Expected bool within_optional_scope, got: {} '
                              u'{}'.format(type(self.within_optional_scope).__name__,
                                           self.within_optional_scope))
docs: Ensure that the Traverse block is valid.