public boolean belongsToConditionalExpression(@NotNull PsiElement regexpElement, @NotNull PsiElement hostElement) {
    final RegExpLanguageHost host = findRegExpHost(regexpElement);
    return host != null && host.belongsToConditionalExpression(hostElement);
  }
public boolean belongsToConditionalExpression(@NotNull PsiElement regexpElement, @NotNull PsiElement hostElement)