code: def save_file(self, filename, target_name=None):
      target_name = target_name or os.path.basename(filename)
      key = s3_join(self.dir, target_name)
      self.put_data(key, open(filename, "rb"))
  
imports: import json
  import os
  import os.path
  from sacred.commandline_options import cli_option
  from sacred.dependencies import get_digest
  from sacred.observers.base import RunObserver
  from sacred.serializer import flatten
  import re
  import socket
label_desc: Use image node_id 13 for calling the S3Observer obj's underlying member method code with example usage: obj.save_file(filename, target_name) without return types