code: def cpu_count():
      
      num = os.getenv("OMP_NUM_THREADS")
      if num is None:
          num = os.getenv("PBS_NUM_PPN")
      try:
          return int(num)
      except:
          return multiprocessing.cpu_count()
docs: Returns the default number of slave processes to be spawned.
  
          The default value is the number of physical cpu cores seen by python.
          :code:`OMP_NUM_THREADS` environment variable overrides it.
  
          On PBS/torque systems if OMP_NUM_THREADS is empty, we try to
          use the value of :code:`PBS_NUM_PPN` variable.
  
          Notes
          -----
          On some machines the physical number of cores does not equal
          the number of cpus shall be used. PSC Blacklight for example.