REGEXP_FILE
  RegExpPatternImpl: <[a-a]>
    RegExpBranchImpl: <[a-a]>
      RegExpClassImpl: <[a-a]>
        PsiElement(CLASS_BEGIN)('[')
        RegExpCharRangeImpl: <a-a>
          RegExpCharImpl: <a>
            PsiElement(CHARACTER)('a')
          PsiElement(MINUS)('-')
          RegExpCharImpl: <a>
            PsiElement(CHARACTER)('a')
        PsiElement(CLASS_END)(']')