code: def worker_pool():
      """use the 'worker pool' strategy; hence one job is allocated to each
      worker, and the next new work item is provided when a node completes its work
      """
      # from mpi_pool import parallel_map as map
      # return map
      return "mpi_pool"
  
imports: import os
label_desc: Use image node_id 3 for calling a global function with example usage: worker_pool() and returns: str