code: def to_json(self, base_dir=None):
      if base_dir:
          return (
              os.path.relpath(
                  self.filename, os.path.realpath(base_dir)
              ),
              self.digest,
          )
      else:
          return self.filename, self.digest
  
imports: import functools
  import hashlib
  import os.path
  import re
  import sys
  from pathlib import Path
  import pkg_resources
  import sacred.optional
  from sacred import SETTINGS
  from sacred.utils import iter_prefixes
label_desc: Use image node_id 3 for calling the Source obj's underlying member method code with example usage: obj.to_json(base_dir) and returns: os,  self, self,  self