code: def lock(self):
      value = self.counter.next(+1)
      while value != 0:
          value = self.counter.next(-1)
          value = self.counter.next(+1)
  
file_path: mpi4py/demo/nxtval/nxtval-scalable.py
imports: from mpi4py import MPI
  import struct
label_desc: Use image node_id 5 for calling the Mutex obj's underlying member method code with example usage: obj.lock() without return types