anchor.diff:      ;
   
   selectorSequence
  -    : ( typeSelector | universal ) ( id | className | attrib | pseudo | negation | interpolation ( variableName | Percentage )? | parent )*
  -    | ( id | className | attrib | pseudo | negation | interpolation ( variableName | Percentage )? | parent )+
  +    : ( typeSelector | universal ) ( id | className | attrib | pseudo | negation | interpolation ( variableName | Percentage )? | parentRef )*
  +    | ( id | className | attrib | pseudo | negation | interpolation ( variableName | Percentage )? | parentRef )+
       ;
   
   id
  
positive.code:     ;
  
  interpolation
      : namespace_? Hash BlockStart namespace_? ( ifExpression | value | parent ) BlockEnd measurment?
      ;
  
  parent
      : Amp
      ;
  
  
negative.code:     ;
  
  extendDeclaration
      : Extend ws ( Percentage | parentRef )?
      ( id | typeSelector | universal | className | attrib | pseudo | interpolation | parentRef )+ ws Semi? ws
      ;
  
  warndingDeclaration
  