anchor.diff:  
   mode DQ_GSTRING_MODE;
   GStringEnd
  -    :   '"'     -> popMode
  +    :   GStringQuotationMark     -> popMode
       ;
   GStringPart
       :   Dollar  -> pushMode(GSTRING_TYPE_SELECTOR_MODE)
  
positive.code: fragment
  Dollar
      :   '$'
      ;
  
  fragment
  
negative.code: // character in the triple double quotation string. e.g. """a"""
  fragment TdqStringCharacter
      :   ~["\\$]
      |   GStringQuotationMark { !(_input.LA(1) == '"' && _input.LA(2) == '"') }?
      |   EscapeSequence
      ;
  
  // character in the triple single quotation string. e.g. '''a'''
  fragment TsqStringCharacter
      :   ~['\\]
      |   SqStringQuotationMark { !(_input.LA(1) == '\'' && _input.LA(2) == '\'') }?
      |   EscapeSequence
      ;
  
  