anchor.diff:     ;
   
   signals
  -   : 'signals' exception (',' exception)*
  +   : 'signals' '(' exception (',' exception)* ')'
      ;
   
   exception
  
positive.code:    ;
  
  field_spec
     : name (',' name)* type_spec
     ;
  
  statement
  
negative.code:    ;
  
  cluster_body
     : equate* 'rep' '=' type_spec equate* own_var* 'routine' routine*
     ;
  
  routine
  