           "#{@val}"
       })
 
-
     class ExpressionToString
       initialize: (@expression)->
       toString: ->
-        ref.refine(@expression).toString()
+        ref.refine(@expression).toString(false)
       toHTMLString: ->
-        ref.refine(@expression).toHTMLString()
+        ref.refine(@expression).toHTMLString(false)
 
     class_mixer ExpressionToString
 

        "&times;"
      });

    ref.forType(comps.subtraction, {
      toString: ->
        "*"

      })

    ref.forType(comps.expression, {
      toString: (wrap_with_parentheses=true)->
        ret = @mapconcatWithMethod('toString')
        @maybeWrapWithParentheses(ret, wrap_with_parentheses)
      toHTMLString: (wrap_with_parentheses=true)->
        ret = @mapconcatWithMethod('toHTMLString')
        @maybeWrapWithParentheses(ret, wrap_with_parentheses)

      mapconcatWithMethod: (method)->
        _(@expression).map((it)-> ref.refine(it)[method]()).join(' ')
      maybeWrapWithParentheses: (str, do_wrap)->
        if do_wrap
          "( #{str} )"
        else
          str
      });

    ref.forType(comps.blank, {
