Код урока

interface Football {
	cloth: string;
	score: string;
	getSportName: () => 'Football';
	getFootballString: () => 'Football string';
}

interface Hockey {
	cloth: string;
	score: string;
	getSportName: () => 'Hokey';
	getHockeyString: () => 'Hockey string';	
}


function func(): Football | Hockey {
	// code
}

let sport = func();
sport.getSportName();
// sport.getFootballString();

// утверждение типа
if((<Football>sport).getFootballString) {
	(<Football>sport).getFootballString();
}