docs: async function signup (username, password, options = {}) {
      let { email = null, profile = {}, roles = [] } = options
      let user = await User.create({ username, email })
      user.sign = await UserSign.create({ user, password })
      user.profile = await UserProfile.create({ user, profile })
      user.roles = await UserRole.createBulk(roles.map((code) => ({ user, code })))
      await user.save()
      return user
    }