# File lib/yard/handlers/ruby/mixin_handler.rb, line 23
  def process_mixin(mixin)
    raise YARD::Parser::UndocumentableError unless mixin.ref?
    raise YARD::Parser::UndocumentableError if mixin.first.type == :ident

    case obj = Proxy.new(namespace, mixin.source)
    when ConstantObject # If a constant is included, use its value as the real object
      obj = Proxy.new(namespace, obj.value, :module)
    else
      obj = Proxy.new(namespace, mixin.source, :module)
    end

    namespace.mixins(scope).unshift(obj) unless namespace.mixins(scope).include?(obj)
  end