Good part of typescript namespace

Something.ts

export interface Something {
  rules: Something.Rule[];
}

export namespace Something {
  /**
   * Rule is a pretty common name
   * use namespace so we can easily avoid name collision without named import like
   * import { Rule as ARule } from ./Something;
   * import { Rule as BRule } from ./Otherthing;
   */
  export interface Rule {}

  export const isValid = (v: Something): boolean => {
    return Boolean(v.rules.length);
  };

  export const defaultRules = (): Rule[] => {
    return [{}];
  };
}

test.ts

import { Something } from './Something';

class B implements Something {
  rules: Something.Rule[] = Something.defaultRules();
}

const b = new B();

const isValid = Something.isValid(b);