code: def physical_cpus():
      
      if platform.system() == 'Darwin':
          ncores = subprocess.check_output(
              ['/usr/sbin/sysctl', '-n', 'hw.ncpu'], shell=False
          )
          return int(ncores.strip())
  
      sockets = set()
      with open('/proc/cpuinfo') as istr:
          for line in istr:
              if line.startswith('physical id'):
                  sockets.add(line.split(':')[-1].strip())
      return len(sockets)
docs: Get cpus identifiers, for instance set(["0", "1", "2", "3"])
  
      :return Number of physical CPUs available
      :rtype: int