anchor.diff:  /*
    * alexsaveliev: added comma-separate tokens to support
    * @available(*, unavailable, message="Please wrap your tuple argument in parentheses: 'print((...))'")
  + * alexsaveliev: multiple identiiers/literals in a row to support "@available(iOS 9.0, OSX 10.11, *)"
    */
   balanced_tokens
    : balanced_token+
  
positive.code:  : '('  balanced_tokens? ')'
   | '[' balanced_tokens? ']'
   | '{' balanced_tokens? '}'
   | identifier | expression | context_sensitive_keyword | literal | operator
  // | Any punctuation except ( ,  ')' , '[' , ']' , { , or } TODO add?
   ;
  
  
negative.code: 
  parenthesized_expression : '(' expression_element_list? ')'  ;
  expression_element_list : expression_element (',' expression_element)* ;
  expression_element : expression | identifier ':' expression | operator ;
  
  // GRAMMAR OF A WILDCARD EXPRESSION
  
  