koss-lebedev/declaration-merging.ts

## declaration-merging.ts
interface IUser {
  firstName: string
  lastName: string
}

interface IUser {
  age: number
}

const user: IUser = {
  firstName: 'Jon',
  lastName: 'Doe',
  age: 25,
}
	interface IUser {
	firstName: string
	lastName: string
	}

	interface IUser {
	age: number
	}

	const user: IUser = {
	firstName: 'Jon',
	lastName: 'Doe',
	age: 25,
	}