code: def reorient_coordinates(self):
          
          # if tree is empty then bail out
          if len(self.ttree) < 2:
              return
  
          # down is the default orientation
          # down-facing tips align at y=0, first ladderized tip at x=0
          if self.ttree.style.orient in ('down', 0):
              pass
  
          # right-facing tips align at x=0, last ladderized tip at y=0
          elif self.ttree.style.orient in ('right', 3):
  
              # verts swap x and ys and make xs 0 to negative
              tmp = np.zeros(self.verts.shape)
              tmp[:, 1] = self.verts[:, 0]
              tmp[:, 0] = self.verts[:, 1] * -1
              self.verts = tmp
  
              # coords...
              tmp = np.zeros(self.coords.shape)
              tmp[:, 1] = self.coords[:, 0]
              tmp[:, 0] = self.coords[:, 1] * -1
              self.coords = tmp
  
          elif self.ttree.style.orient in ('left', 1):
              raise NotImplementedError("todo: left facing")
  
          else:
              raise NotImplementedError("todo: up facing")
docs: Returns a modified .verts array with new coordinates for nodes. 
          This does not need to modify .edges. The order of nodes, and therefore
          of verts rows is still the same because it is still based on the tree
          branching order (ladderized usually).