     '==': '==='
     '!=': '!=='
 
-  # The map of invertable operators.
+  # The map of invertible operators.
   INVERSIONS:
     '!==': '==='
     '===': '!=='

  isUnary: ->
    not @second

  isInvertable: ->
    @operator in ['===', '!==']

  isMutator: ->
    ends(@operator, '=') and not @isInvertable()

  isChainable: ->
    include(@CHAINABLE, @operator)

  constructor: (@condition, @body, @tags) ->
    @tags or= {}
    if @tags.invert
      if @condition instanceof OpNode and @condition.isInvertible()
        @condition.invert()
      else
        @condition = new OpNode '!', new ParentheticalNode @condition
