code: func (c *Client) CreateUserWithU2FToken(token string, password string, u2fRegisterResponse u2f.RegisterResponse) (services.WebSession, error) {
  	out, err := c.PostJSON(c.Endpoint("u2f", "users"), createUserWithU2FTokenReq{
  		Token:               token,
  		Password:            password,
  		U2FRegisterResponse: u2fRegisterResponse,
  	})
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  	return services.GetWebSessionMarshaler().UnmarshalWebSession(out.Bytes())
  }
docs: // CreateUserWithU2FToken creates user account with provided token and U2F sign response