REGEXP_FILE
  RegExpPatternImpl: <([ab]*)b>
    RegExpBranchImpl: <([ab]*)b>
      RegExpGroupImpl: <([ab]*)>
        PsiElement(GROUP_BEGIN)('(')
        RegExpPatternImpl: <[ab]*>
          RegExpBranchImpl: <[ab]*>
            RegExpClosureImpl: <[ab]*>
              RegExpClassImpl: <[ab]>
                PsiElement(CLASS_BEGIN)('[')
                RegExpCharImpl: <a>
                  PsiElement(CHARACTER)('a')
                RegExpCharImpl: <b>
                  PsiElement(CHARACTER)('b')
                PsiElement(CLASS_END)(']')
              RegExpQuantifierImpl: <*>
                PsiElement(STAR)('*')
        PsiElement(GROUP_END)(')')
      RegExpCharImpl: <b>
        PsiElement(CHARACTER)('b')