def extend_to_block_definition(block_definition)
      RuntimeContext.new(builder, block_definition, parent_runtime_context: self).tap do |rc|
        rc.runtime_args = self.runtime_args
      end
    end
def extend_to_block_definition(block_definition)
      RuntimeContext.new(builder, block_definition, parent_runtime_context: self).tap do |rc|
        rc.runtime_args = self.runtime_args
      end
    end
TODO: this method needs to clone without context, i.e. with render_strategy, item, etc