docstr: get current size of replay memory.
          
docstr_tok: ["get","current","size","of","replay","memory","."]
code: def size(self):
      """get current size of replay memory."""
      return self._curr_size
  
file_path: PARL/benchmark/torch/iql/replay_buffer.py
imports: import numpy
  from parl.utils import logger
  import d4rl
  from tqdm import tqdm
label_desc: Use image node_id 3 for calling the ReplayMemory obj's underlying member method code with example usage: obj.size() and returns: self