REGEXP_FILE
  RegExpPatternImpl: <(?iZm)abc>
    RegExpBranchImpl: <(?iZm)abc>
      RegExpSetOptionsImpl: <(?iZm)>
        PsiElement(SET_OPTIONS)('(?')
        RegExpOptionsImpl: <iZm>
          PsiElement(OPTIONS_ON)('iZm')
        PsiElement(GROUP_END)(')')
      RegExpCharImpl: <a>
        PsiElement(CHARACTER)('a')
      RegExpCharImpl: <b>
        PsiElement(CHARACTER)('b')
      RegExpCharImpl: <c>
        PsiElement(CHARACTER)('c')