interface Todo {
  Todo.title: stringtitle: string;
}

const const todo: Readonly<Todo>todo: type Readonly<T> = { readonly [P in keyof T]: T[P]; }
Make all properties in T readonlyReadonly<Todo> = {
  title: stringtitle: "Delete inactive users".String.toUpperCase(): string
Converts all the alphabetic characters in a string to uppercase.toUpperCase(),
};

const todo: Readonly<Todo>todo.
Cannot assign to 'title' because it is a read-only property.title = "Hello";