# File lib/irb/ruby-token.rb, line 250
  def RubyToken.def_token(token_n, super_token = Token, reading = nil, *opts)
    token_n = token_n.id2name if token_n.kind_of?(Symbol)
    if RubyToken.const_defined?(token_n)
      IRB.fail AlreadyDefinedToken, token_n
    end
    token_c = eval("class #{token_n} < #{super_token}; end; #{token_n}")
    
    if reading
      if TkReading2Token[reading]
        IRB.fail TkReading2TokenDuplicateError, token_n, reading
      end
      if opts.empty?
        TkReading2Token[reading] = [token_c]
      else
        TkReading2Token[reading] = [token_c].concat(opts)
      end
    end
    TkSymbol2Token[token_n.intern] = token_c
  end