code: def allocate(self, num_elems, count, dtype):
      assert dtype == self.dtype
      assert num_elems <= self.num_elems
      if count > len(self.free_buffer_index):
          return None
  
      used_indices = self.free_buffer_index[-count:]
      self.free_buffer_index = self.free_buffer_index[:-count]
  
      buffers = []
      for i in used_indices:
          tmp_buffer = self.all_buffers[i].narrow(0, 0, num_elems)
          buffers.append(tmp_buffer)
          self.used_buffer_index[id(tmp_buffer)] = i
      return buffers
  
imports: import torch
  from deepspeed.utils.logging import logger
  from deepspeed import comm
label_desc: Use image node_id 2 for calling the SwapBufferManager obj's underlying member method code with example usage: obj.allocate(num_elems, count, dtype) and returns: buffers, None