code: def node_multiplier(self, multiplier=0.5, seed=None):
          
          random.seed(seed)
          ctree = self._ttree.copy()
          low, high = sorted([multiplier, 1. / multiplier])
          mult = random.uniform(low, high)
          for node in ctree.treenode.traverse():
              node.dist = node.dist * mult
          ctree._coords.update()
          return ctree
docs: Returns a toytree copy with all nodes multiplied by a constant 
          sampled uniformly between (multiplier, 1/multiplier).