code: def sequence_id(self, sequence):
          
          if self.meaningful_ids:
              # TODO: This might fail if the ID becomes too long
              return "><".join([node.id for node in sequence])
          else:
              return getrandbits(64)
docs: Make up an ID for a sequence (list) of nodes.
          Note: `getrandbits()` is very uninformative as a "readable" ID. Here, we build a name
          such that when the mouse hovers over the drawn node in Jupyter, one can figure out
          which original nodes make up the sequence. This is actually quite useful.