code: def connect_signals(self):
          
          # Connect the signals inside each Work.
          for work in self:
              work.connect_signals()
  
          # Observe the nodes that must reach S_OK in order to call the callbacks.
          for cbk in self._callbacks:
              #cbk.enable()
              for dep in cbk.deps:
                  logger.info("connecting %s \nwith sender %s, signal %s" % (str(cbk), dep.node, dep.node.S_OK))
                  dispatcher.connect(self.on_dep_ok, signal=dep.node.S_OK, sender=dep.node, weak=False)
docs: Connect the signals within the `Flow`.
          The `Flow` is responsible for catching the important signals raised from its works.