// And if you just want the string,
std::string result = svformat("The only {what} is {value}", m);
// => "The only answer is 42"
-std::string result = svformat("The only {0[what]} is {0[value]}", m);
+std::string result = sformat("The only {0[what]} is {0[value]}", m);
// => "The only answer is 42"
// {} works for vformat too