parse_visibility

# File lib/rdoc/parsers/parse_rb.rb, line 2482
    def parse_visibility(container, single, tk)
      singleton = (single == SINGLE)
      vis = case tk.name
            when "private"   then :private
            when "protected" then :protected
            when "public"    then :public
            when "private_class_method"
              singleton = true
              :private
            when "public_class_method"
              singleton = true
              :public
            else raise "Invalid visibility: #{tk.name}"
            end
            
      skip_tkspace_comment(false)
      case peek_tk
        # Ryan Davis suggested the extension to ignore modifiers, because he
        # often writes
        #
        #   protected unless $TESTING
        #
      when TkNL, TkUNLESS_MOD, TkIF_MOD
#        error("Missing argument") if singleton        
        container.ongoing_visibility = vis
      else
        args = parse_symbol_arg
        container.set_visibility_for(args, vis, singleton)
      end
    end