code: def collapse_nodes(self, min_dist=1e-6, min_support=0):
          
          nself = self.copy()
          for node in nself.treenode.traverse():
              if not node.is_leaf():
                  if (node.dist <= min_dist) | (node.support < min_support):
                      node.delete()
          nself._coords.update()
          return nself
docs: Returns a copy of the tree where internal nodes with dist <= min_dist
          are deleted, resulting in a collapsed tree. e.g.:
  
          newtre = tre.collapse_nodes(min_dist=0.001)
          newtre = tre.collapse_nodes(min_support=50)