class_docstr: Base class for Requests and Replies.
  
  All subclasses must accept keyword arguments to __init__() corresponding to
  their attributes.
code: def routing(self):
      return "/".join(self._routing)
  
imports: import sys
  import cellprofiler_core.utilities.zmq
label_desc: Use image node_id 3 for calling the Communicable obj's underlying member method code with example usage: obj.routing() and returns: str