docs: def get_pid(pid=None):
      '''get_pid will return a pid of interest. First we use given variable,
      then environmental variable PID, and then PID of running process
      '''
      if pid == None:
          if os.environ.get("PID",None) != None:
              pid = int(os.environ.get("PID"))
          # Then use current running script as process
          else:
              pid = os.getpid()
      print("pid is %s" %pid)
      return pid