def descendent_element_definitions
      definitions = element_definitions_by_name(element_definition_names)
      definitions.select { |d| d.key?('nestable_elements') }.each do |d|
        definitions += element_definitions_by_name(d['nestable_elements'])
      end
      definitions.uniq { |d| d['name'] }
    end
def descendent_element_definitions
      definitions = element_definitions_by_name(element_definition_names)
      definitions.select { |d| d.key?('nestable_elements') }.each do |d|
        definitions += element_definitions_by_name(d['nestable_elements'])
      end
      definitions.uniq { |d| d['name'] }
    end
All element definitions defined for page's page layout including nestable element definitions