REGEXP_FILE
  RegExpPatternImpl: <\p{Digit}+>
    RegExpBranchImpl: <\p{Digit}+>
      RegExpClosureImpl: <\p{Digit}+>
        RegExpPropertyImpl: <\p{Digit}>
          PsiElement(PROPERTY)('\p')
          PsiElement(LBRACE)('{')
          PsiElement(NAME)('Digit')
          PsiElement(RBRACE)('}')
        RegExpQuantifierImpl: <+>
          PsiElement(PLUS)('+')