anchor.diff:      :   '<<' 'else' '>>' block*
       ;
   
  -endIfStmt
  +endStmt
       :   '<<' 'end' '>>'
       ;
   
  
positive.code:     :   '<<' 'for' wsa variable 'in' expr '>>' NL? block*
      //|   '<<' 'for' wsa key=variable ',' val=variable 'in' expr '>>' NL? block*
      |   '<<' 'for' wsa variable 'in' interval '>>' NL? block*
      ;
  
  endForStmt
      :   '<<' 'end' '>>'
      ;
  
  expr
  
negative.code: 
  // if, elif, else, for, end
  controlStmt
      :   ifStmt (elifStmt)* (elseStmt)? endStmt  # ifCtrlStmt
      |   forStmt endStmt                         # forCtrlStmt
      ;
  
  ifStmt
  