anchor.diff:  
   // GRAMMAR OF OPERATORS
   
  -Operator : Operator_character+ ;
  -fragment Operator_character : [/=\-+!*%<>&|^!.] ;
  +Operator : [/=\-+!*%<>&|^!.]+ ;
   binary_operator : Operator ;
   prefix_operator : Operator  ;
   postfix_operator : Operator  ;
  
positive.code: // GRAMMAR OF A CONSTANT DECLARATION
  
  constant_declaration : attributes? declaration_specifiers? 'let' pattern_initializer_list  ;
  pattern_initializer_list : pattern_initializer | pattern_initializer ',' pattern_initializer_list  ;
  pattern_initializer : pattern initializer? ;
  initializer : '=' expression  ;
  
  
negative.code: 
  // GRAMMAR OF A FOR STATEMENT
  
  for_statement
   : 'for' for_init? ';' expression? ';' expression? code_block
   | 'for' ( for_init?';' expression?';' expression?) code_block
   ;
  for_init : variable_declaration | expression_list  ;
  