class Racc::Grammar::DefinitionEnv

def _add(target, x)
  case x
  when Sym
    @delayed.each do |rule|
      rule.replace x, target if rule.target == x
    end
    @grammar.symboltable.delete x
  else
    x.each_rule do |r|
      r.target = target
      @grammar.add r
    end
  end
  flush_delayed
end