anchor.diff:      ;
   
   existenceEmptinessExpression
  -    : dateCompositionExpression ('exists' | 'nonempty')?
  +    : rangeIntervalEntryExpression ('exists' | 'nonempty')?
       ;
   
   //I wonder if it would it be cleaner to give 
  
positive.code:     ;
  
  typeParameters
      : '<' type (',' type)* '>'
      ;
  
  //for locals and attributes
  initializer
      : ('=' | ':=') assignable
  
negative.code:     ;
  
  elementsSpec
      : additiveExpression ( '...' | '..' additiveExpression | (',' additiveExpression)+ )?
      |  '...' additiveExpression	
      ;
  
  arguments 
  