docstr: parallel reduce followed by broadcast of the result
docstr_tok: ["parallel","reduce","followed","by","broadcast","of","the","result"]
code: def allreduce(self, f, value, flat=True):
      """parallel reduce followed by broadcast of the result"""
      return self.reduce(f, value, flat=flat, all=True)
  
imports: import re
  import socket
  from functools import reduce
  import zmq
  from ipyparallel.serialize import deserialize_object, serialize_object
  from ipyparallel.util import disambiguate_url
label_desc: Use image node_id 12 for calling the BinaryTreeCommunicator obj's underlying member method code with example usage: obj.allreduce(f, value, flat) and returns: self