docs: def set_items_sequential(self, sequential):
          """Sets the items sequential flag.
  
          arg:    sequential (boolean): ``true`` if the items are taken
                  sequentially, ``false`` if the items can be skipped and
                  revisited
          raise:  InvalidArgument - ``sequential`` is invalid
          raise:  NoAccess - ``Metadata.isReadOnly()`` is ``true``
          *compliance: mandatory -- This method must be implemented.*
  
          """
          # Implemented from template for osid.resource.ResourceForm.set_group_template
          if self.get_items_sequential_metadata().is_read_only():
              raise errors.NoAccess()
          if not self._is_valid_boolean(sequential):
              raise errors.InvalidArgument()
          self._my_map['itemsSequential'] = sequential