Worker class
          #include <taskflow/core/worker.hpp>
        
        class to create a worker in an executor
The class is primarily used by the executor to perform work-stealing algorithm. Users can access a worker object and alter its property (e.g., changing the thread affinity in a POSIX-like system) using tf::
Public functions
- auto id() const -> size_t
- queries the worker id associated with its parent executor
- auto queue_size() const -> size_t
- queries the size of the queue (i.e., number of enqueued tasks to run) associated with the worker
- auto queue_capacity() const -> size_t
- queries the current capacity of the queue
- auto executor() -> Executor*
- acquires the associated executor
- 
              auto thread() -> std::thread& 
- acquires the associated thread
Function documentation
              size_t tf::
            queries the worker id associated with its parent executor
A worker id is a unsigned integer in the range [0, N), where N is the number of workers spawned at the construction time of the executor.