anchor.diff:  assertDecl
      : 'assert' name? block
      ;
  -
  +   // qualname | bloclk should be optional
  +   
   cmdDecl
  -   : (name ':')? ('run' | 'check')? (qualName | block)? scope?
  +   : (name ':')? ('run' | 'check')? (qualName | block) scope?
      ;
   
   scope
  
positive.code:    | block
     ;
  
  const
     : '-'? number
     | 'none'
     | 'univ'
  
negative.code:    ;
  
  expr
     : const_
     | qualName
     | '@' name
     | 'this'
     | unOp expr
     | expr binOp expr
     | expr arrowOp expr
     | expr (',' expr)+
     | expr ('!' | 'not') compareOp expr
     | expr ('=>' | 'implies') expr 'else' expr
     | 'let' letDecl (',' letDecl)* blockOrBar
  