import*as levenshtien from'damerau-levenshtein';interfaceLevenshteinResponse { steps:number; relative:number; similarity:number;}constlev:LevenshteinResponse=levenshtien('hello world','Hello World!');console.log(lev.steps);// 2console.log(lev.foo);// TypeScript Error: Property 'foo' does not exist on type 'LevenshteinResponse'.