anchor.diff:  
   fragment
   ESC : '\'\'' ;
  +
  
positive.code: expr
      : expr '(' exprList ')'
      | expr ('\''|'.\''|'.^'|'^') expr
      | ('+'|'-''~') expr
      | expr ('*'|'.*'|'/'|'./'|'\\'|'.\\') expr
      | expr ('+'|'-') expr
      | expr ':' expr
  
negative.code: ifStat
      : 'if' expr endStat statBlock 
        ('elseif' expr endStat statBlock)* 
        ('else' endStat? statBlock)?
        'end'
      ;
  
  