code: def getDepth(self, node):
      if node is None:
          return 1
      ld = self.getDepth(node.left)
      if ld < 0:
          return -1
      rd = self.getDepth(node.right)
      if rd < 0:
          return -1
      elif abs(ld - rd) > 1:
          return -1
      else:
          return max(ld, rd) + 1
  
label_desc: Use image node_id 2 for calling the Solution obj's underlying member method code with example usage: obj.getDepth(node) and returns: int, unknown, unknown, unknown, unknown