code: def process_affinity(affinity=None):
      
      if affinity is not None:
          affinity = CPUSet(affinity)
          if not affinity.issubset(system_affinity()):
              raise ValueError("unknown cpus: %s" % affinity)
      return system_affinity()
docs: Get or set the CPU affinity set for the current process.
  
      This will affect all future threads spawned by this process.  It is
      implementation-defined whether it will also affect previously-spawned
      threads.