code: def sample(self, batch_size):
      indices = np.random.choice(min(self.idx, self.size), batch_size)
      return self.memory[indices]
  
file_path: dynet/examples/reinforcement-learning/memory.py
imports: import numpy
  from math import log, ceil
  from reduce_tree import ReduceTree, SumTree
label_desc: Use image node_id 3 for calling the Memory obj's underlying member method code with example usage: obj.sample(batch_size) and returns: self