anchor.diff:      | PLUS
       ;  
       
  -operator
  -    : SOLIDUS
  -    | COMMA
  -    ;
  -    
  -
  -hexColor
  + */   
  +
  +hexColor 
       : HASH
       ;
       
  -function
  -    : IDENT LPAREN expr RPAREN
  -    ;
  -    
  +ident    
  +    : IDENT 
  +    | ALPHA 
  +    | EXPRESSION 
  +    ;
  +
   // ==============================================================
   // LEXER
   //
  
positive.code:     ;
              
  ruleSet
      : selector (WS* COMMA WS* selector)* WS* LBRACE (WS* declaration)* WS* RBRACE
      -> ^(RULESET ^(SELECTOR selector)+ declaration*)
      ;
  
  selector
  
negative.code: important
      : IMPORTANT_SYM
      ;
  /*    
  expr 
      : term ((WS+|WS* operator WS*) term)*
      ;
  
  term
      : additiveExpression
      | unaryOperator?
          (
                NUMBER
              | PERCENTAGE
  