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#include <boost/variant.hpp>#include <string>#include <iostream>class boolean_visitor : boost::static_visitor<bool> {public:	bool operator()( int& i ) {		if( i == 0 ) { return false; }		return true;	}		bool operator()( std::string& str ) {		if( str.empty() ) { return false; }		return true;	}		bool operator()( float& f ) {		if( f == 0.0 ) { return false; }		return true;	}};int main( int argc, char** argv ) {	boost::variant< int, std::string, float > cvar;		cvar = "Hello, World!";	std::cout << cvar << std::endl;	if( boost::apply_visitor( boolean_visitor(), cvar ) ) {		std::cout << "true" << std::endl;	}	cvar = 0;	std::cout << cvar << std::endl;	if( boost::apply_visitor( boolean_visitor(), cvar ) ) {		std::cout << "true" << std::endl;	}	cvar = 3.14f;	std::cout << cvar << std::endl;	if( boost::apply_visitor( boolean_visitor(), cvar ) ) {		std::cout << "true" << std::endl;	}	return( 0 );}