anchor.diff:      | functionImplementation
       | onImplementation
       | eventDeclaration
  -   // | eventImplementation
  +    | eventImplementation
       ;
   
   // 1. Forward Declaration
  
positive.code: 
  // 11. Event Declaration
  eventDeclaration
      : 'event' eventTypeDeclaration Identifier? parametersList
      ;
  
  eventTypeDeclaration
      : 'type'
      | creatorType
      ;
  	
  creatorType
      : 'create'
      | 'destroy'
      ;
  
  parametersList
      : '(' parametersDeclarators? ')'
  
negative.code:     |   'DATE'
      |   'DATETIME'
      |   'DECIMAL'
      |   'dec'
      |   'DOUBLE'
      |   'integer'
      |   'int'
      |   'long'
      |   'longlong'
      |   'real'
      |   'string'
      |   'TIME'
      |   'UNSIGNEDINTEGER'
      |   'UINT'
  