// javascript
const solution = (my_strings, parts) => {
return my_strings.map((item, index) => item.slice(parts[index][0], parts[index][1] + 1)).join('');
}
// typescript
const solution = (my_strings: string[], parts: [number, number][]): string => {
return my_strings
.map((item, index) => item.slice(parts[index][0], parts[index][1] + 1))
.join('');
};