REGEXP_FILE
  RegExpPatternImpl: <\[\]$>
    RegExpBranchImpl: <\[\]$>
      RegExpCharImpl: <\[>
        PsiElement(ESC_CHARACTER)('\[')
      RegExpCharImpl: <\]>
        PsiElement(REDUNDANT_ESCAPE)('\]')
      RegExpBoundaryImpl: <$>
        PsiElement(DOLLAR)('$')