StringNoNumbersSpecial = t.refinement(t.String, value => {
      const reg = /^[a-zA-Z]*$/
      return reg.test(value)
    })

    Email = t.refinement(t.String, email => {
      const reg = /[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/; //or any other regexp
      return reg.test(email);
    });

    this.User = t.struct({
      firstName: StringNoNumbersSpecial,
      lastName: StringNoNumbersSpecial,
      address: StringNoNumbersSpecial,
      city: StringNoNumbersSpecial,
      dateOfBirth: t.Date,
      email: Email,
      password: PasswordMinLength,
      reEnterPassword: ConfirmPasswordEquality,
    });