# File lib/asciidoctor/abstract_node.rb, line 221
  def add_role(name)
    if (val = @attributes['role']).nil_or_empty?
      @attributes['role'] = name
      true
    # NOTE center + include? is faster than split + include?
    elsif %( #{val} ).include?(%( #{name} ))
      false
    else
      @attributes['role'] = %(#{val} #{name})
      true
    end
  end