token_extraction.go
func FromParams(r *http.Request) (*jwt.JSONWebToken, error) {
	if r == nil {
		return nil, ErrNilRequest
	}
	raw := r.URL.Query().Get("token")
	if raw == "" {
		return nil, ErrTokenNotFound
	}
	return jwt.ParseSigned(raw)
}
func FromParams(r *http.Request) (*jwt.JSONWebToken, error) {
	if r == nil {
		return nil, ErrNilRequest
	}
	raw := r.URL.Query().Get("token")
	if raw == "" {
		return nil, ErrTokenNotFound
	}
	return jwt.ParseSigned(raw)
}
// FromParams returns the JWT when passed as the URL query param "token".