code: def next(self, increment=1):
      _array_set(self.acc_buf, increment)
      root = 0
      self.win.Lock(root)
      self.win.Get(self.get_buf, root, [0, 1, self.get_type])
      self.win.Accumulate(
          self.acc_buf, root, [0, 1, self.acc_type], MPI.SUM
      )
      self.win.Unlock(root)
      nxtval = self.myval + _array_sum(self.get_buf)
      self.myval += increment
      return nxtval
  
file_path: mpi4py/demo/nxtval/nxtval-scalable.py
imports: from mpi4py import MPI
  import struct
label_desc: Use image node_id 3 for calling the Counter obj's underlying member method code with example usage: obj.next(increment) and returns: nxtval