class_docstr: Accumulator for loss statistics.
  Currently calculates:
  
  * accuracy
  * perplexity
  * elapsed time
docstr: compute elapsed time
docstr_tok: ["compute","elapsed","time"]
code: def elapsed_time(self):
      """compute elapsed time"""
      return time.time() - self.start_time
  
file_path: OpenNMT-py/onmt/utils/statistics.py
imports: import time
  import math
  import sys
  from onmt.utils.logging import logger
label_desc: Use image node_id 8 for calling the Statistics obj's underlying member method code with example usage: obj.elapsed_time() and returns: unknown