anchor.diff:  fragment NOT_LINE_TERMINATOR : ~('\r' | '\n');
   COMMENT : '%' | '%' ~'{' NOT_LINE_TERMINATOR*;
   
  +SHELL_COMMAND : '!' NOT_LINE_TERMINATOR*;
  +
   LINE_TERMINATOR : '\r' '\n' | '\r' | '\n';
   
   fragment ELLIPSIS_COMMENT : '...' NOT_LINE_TERMINATOR* LINE_TERMINATOR;
  
positive.code: RCURLY : '}';
  LSQUARE : '[';
  RSQUARE : ']';
   
  //NB: matched AFTER transpose
  fragment STRING_CHAR : ~('\'' | '\r' | '\n') | '\'\'';
  
negative.code: colon_expr :
       plus_expr (t_FILLER? t_COLON t_FILLER? plus_expr (t_FILLER? t_COLON t_FILLER? plus_expr)?)?
    ;
    
  plus_expr :
       binary_expr (t_FILLER? (t_PLUS | t_MINUS) t_FILLER? binary_expr)*
    ;
  