 
       expect(open).toBeInstanceOf @components.classes.expression
       expect(open.isOpen()).toEqual true
-
 
       ten = open.first()
       expect(ten).toBeInstanceOf @components.classes.number

    expect(sub_exp).toBeInstanceOf @components.classes.expression


  describe "fraction handling", ->
    it "handles base case", ->
      expression = @builder({fraction: [1, 2]})
      sub_exp = expression.first()
      expect(expression).toBeInstanceOf @components.classes.expression
      expect(sub_exp).toBeInstanceOf @components.classes.fraction

  describe "open expressions", ->
    it "uses object syntax with label 'open_expression' to signify an open expression", ->

      expect(ten.value()).toEqual 10




  describe "building with position", ->
    describe "position as last", ->
      it "works", ->
