code: func GetSigningMethod(alg string) (method SigningMethod) {
  	signingMethodLock.RLock()
  	defer signingMethodLock.RUnlock()
  
  	if methodF, ok := signingMethods[alg]; ok {
  		method = methodF()
  	}
  	return
  }
docs: // Get a signing method from an "alg" string