docs: def prune_node(self, node, remove_backrefs=False):
          """
          remove node `node` from the network (including any edges that may
          have been pointing at `node`).
          """
          if not remove_backrefs:
              for fro, connections in self.edges.items():
                  if node in self.edges[fro]:
                      raise ValueError("""Attempting to remove a node with
                                       backrefs. You may consider setting
                                       `remove_backrefs` to true.""")
  
          # OK. Otherwise, let's do our removal.
  
          self.nodes.remove(node)
          if node in self.edges:
              # Remove add edges from this node if we're pruning it.
              self.edges.pop(node)
  
          for fro, connections in self.edges.items():
              # Remove any links to this node (if they exist)
              if node in self.edges[fro]:
                  # If we should remove backrefs:
                  self.edges[fro].remove(node)