class_docstr: GPU Sampler for heterogeneous graph 
class_docstr_tok: ["GPU","Sampler","for","heterogeneous","graph"]
code: def __init__(self, graph_list, sample_list, uva=False):
      raise NotImplementedError
  
imports: import time
  import copy
  import numpy
  import paddle
  import pgl
  from pgl import graph_kernel
  from pgl.sampling.custom import subgraph
  from pgl.utils.logger import log
  from pgl.utils.helper import to_paddle_tensor
label_desc: Use image node_id 1 to create a new HeteroNeighborSampler object from inherited base classes: object with example: obj = HeteroNeighborSampler(graph_list, sample_list, uva)