如何定义boost::any operator ==

#include <boost/any.hpp>
#include <iostream>

int main() {
    boost::any a1 = 10;
    boost::any a2 = 20;
    boost::any a3 = 10;

    if (a1 == a2) {
        std::cout << "a1 and a2 are equal" << std::endl;
    } else {
        std::cout << "a1 and a2 are not equal" << std::endl;
    }

    if (a1 == a3) {
        std::cout << "a1 and a3 are equal" << std::endl;
    } else {
        std::cout << "a1 and a3 are not equal" << std::endl;
    }

    return 0;
}

a1 and a2 are not equal
a1 and a3 are equal