#include <algorithm>#include <format>#include <iomanip>#include <iostream>#include <sstream>#include <string_view> struct QuotableString:std::string_view{}; template<>struct std::formatter<QuotableString,char>{bool quoted=false; template<class ParseContext>constexpr ParseContext::iterator parse(ParseContext& ctx){auto it= ctx.begin();if(it== ctx.end())return it; if(*it=='#'){            quoted=true;++it;}if(it!= ctx.end()&&*it!='}')throwstd::format_error("Invalid format args for QuotableString."); return it;} template<class FmtContext>    FmtContext::iterator format(QuotableString s, FmtContext& ctx)const{std::ostringstream out;if(quoted)            out<<std::quoted(s);else            out<< s; return std::ranges::copy(std::move(out).str(), ctx.out()).out;}}; int main(){    QuotableString a("be"), a2(R"( " be" )");    QuotableString b("a question");std::cout<<std::format("To {0} or not to {0}, that is {1}.\n", a, b);std::cout<<std::format("To {0:} or not to {0:}, that is {1:}.\n", a, b);std::cout<<std::format("To {0:#} or not to {0:#}, that is {1:#}.\n", a2, b);}

To be or not to be, that is a question.To be or not to be, that is a question.To " \" be \" " or not to " \" be \" ", that is "a question".