anchor.diff:  
   StringLiteral
       :   '"' StringCharacters? '"'
  -    |   '\'' StringCharacters? '\''
       ;
   
   fragment
  
positive.code:     ;
  
  inline
      :   '{' statement (';' statement)* '}'
      ;
  
  statements
  
negative.code:     |   PRINT '(' expression ')'
      |   DEBUG '(' expression ')'
      |   TRACE '(' expression ')'
      |   func
      |   call
      |   expression '.' Identifier
      |   expression '[' expression ']'
      |   expression ('++' | '--')
      |   ('+'|'-'|'++'|'--') expression
      |   ('~'|'!') expression
  