old_contents: import collections
  import os
  
  import wandb
  from wandb import util
  
  
  class JsonlFile(object):
      """Used to store data that changes over time during runs. """
  
      def __init__(self, fname, out_dir='.'):
          self.fname = os.path.join(out_dir, fname)
          self._file = open(self.fname, 'w')
          self.rows = []
  
      def keys(self):
          if self.rows:
              return self.rows[0].keys()
          return []
  
      def column(self, key):
          return [r[key] for r in self.rows]
  
      def add(self, row):
          if not isinstance(row, collections.Mapping):
              raise wandb.Error('history.add expects dict-like')
          self.rows.append(row)
          self._file.write(util.json_dumps_safer(row))
          self._file.write('\n')
          self._file.flush()
  
new_contents: import collections
  import os
  import time
  
  import wandb
  from wandb import util
  
  
  class JsonlFile(object):
      """Used to store data that changes over time during runs. """
  
      def __init__(self, fname, out_dir='.'):
          self._start_time = time.time()
          self.fname = os.path.join(out_dir, fname)
          self._file = open(self.fname, 'w')
          self.rows = []
  
      def keys(self):
          if self.rows:
              return self.rows[0].keys()
          return []
  
      def column(self, key):
          return [r[key] for r in self.rows]
  
      def add(self, row):
          if not isinstance(row, collections.Mapping):
              raise wandb.Error('history.add expects dict-like')
          row['_runtime'] = time.time() - self._start_time
          self.rows.append(row)
          self._file.write(util.json_dumps_safer(row))
          self._file.write('\n')
          self._file.flush()
  
subject: Add _runtime to history