anchor.diff:  STATIC_IF: 'static_if';
   THEN: 'then';
   ELSE: 'else';
  -ENDIF: 'endif';
  +ENDIF: 'end_if';
   UNIT: 'unit';
   PLUS: '+';
   MINUS: '-';
  
positive.code: FALSE: 'false';
  ALIAS: 'alias';
  LET: 'let';
  
  // literals
  fragment ESC: '\\"' | '\\\\';
  
negative.code: BAND: '&';
  OR: 'or';
  AND: 'and';
  XOR: '^'; // only binary
  EQUALS: '==';
  NOT_EQ: '!=';
  ASSIGN: '=';
  