WorkerView class
          #include <taskflow/core/worker.hpp>
        
        class to create an immutable view of a worker
An executor keeps a set of internal worker threads to run tasks. A worker view provides users an immutable interface to observe when a worker runs a task, and the view object is only accessible from an observer derived from 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 pending tasks to run) associated with the worker
- auto queue_capacity() const -> size_t
- queries the current capacity of the queue
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.