code: def get(self, master_id):
          
          collection_name = self.request.headers.get("collection")
          self.client = BaseAsyncMotorDocument("%s_revisions" % collection_name)
  
          limit = self.get_query_argument("limit", 2)
          add_current_revision = self.get_arg_value_as_type("addCurrent",
                                                            "false")
          show_history = self.get_arg_value_as_type("showHistory", "false")
  
          objects_processed = []
  
          if isinstance(limit, unicode):
              limit = int(limit)
  
          objects = yield self.client.find({"master_id": master_id,
                                            "processed": False},
                                           orderby="toa",
                                           order_by_direction=1,
                                           page=0,
                                           limit=20)
  
          # If this is a document that should have a revision and doesn't we
          # orchestratioin creation of the first one
          if len(objects) == 0:
  
              new_revision = yield self.__lazy_migration(master_id)
              if not new_revision:
                  return
  
          if show_history:
              objects_processed = yield self.client.find({"master_id": master_id,
                                                          "processed": True},
                                                         orderby="toa",
                                                         order_by_direction=-1,
                                                         page=0,
                                                         limit=limit)
  
          elif add_current_revision:
              objects_processed = yield self.client.find({"master_id": master_id,
                                                          "processed": True},
                                                         orderby="toa",
                                                         order_by_direction=-1,
                                                         page=0,
                                                         limit=1)
  
          if len(objects_processed) > 0:
              objects_processed = objects_processed[::-1]
              objects_processed[-1]["current"] = True
              objects = objects_processed + objects
  
          self.write({
              "count": len(objects),
              "results": objects
          })
docs: Get a list of revisions by master ID
  
          :param master_id:
          :return: