anchor.diff:      :   block
       |   ';'
       |   IDENTIFIER ':' statement
  -	|   expression  ';'     
  +    |   expression  ';'     
       |   'if' parExpression statement ('else' statement)?          
       |   'assert'  expression (':' expression)? ';'            
       |   'switch' parExpression '{' switchBlockStatementGroups '}'
  
positive.code:     :   ('0'..'3')
      ;
  
  // 3.10.7 The Null Literal
  
  NullLiteral
      :   'null'
  
negative.code:     |   '_'
      ;
  
  // ��3.10.2 Floating-Point Literals
  
  FloatingPointLiteral
      :   DecimalFloatingPointLiteral
  