code: public static CallStackElement activateProfiling(String signature) {
  		CallStackElement root = CallStackElement.createRoot(signature);
  		methodCallParent.set(root);
  		return root;
  	}
docs: Activates the profiling for the current thread by setting the provided
  {@link CallStackElement} as the root of the call stack
  
  @return the root of the call stack