# File lib/rbreadline.rb, line 4569
  def _rl_unget_char(key)
    if (ibuffer_space()!=0)
      @pop_index-=1
      if (@pop_index < 0)
        @pop_index = @ibuffer_len - 1
      end
      @ibuffer[@pop_index] = key
      return (1)
    end
    return (0)
  end