REGEXP_FILE
  RegExpPatternImpl: <a{2}>
    RegExpBranchImpl: <a{2}>
      RegExpClosureImpl: <a{2}>
        RegExpCharImpl: <a>
          PsiElement(CHARACTER)('a')
        RegExpQuantifierImpl: <{2}>
          PsiElement(LBRACE)('{')
          RegExpNumberImpl: <2>
            PsiElement(NUMBER)('2')
          PsiElement(RBRACE)('}')