code: def default_extension(environ=None):
      """
      Get the path to the default zipline extension file.
  
      Parameters
      ----------
      environ : dict, optional
          An environment dict to forwart to zipline_root.
  
      Returns
      -------
      default_extension_path : str
          The file path to the default zipline extension file.
      """
      return zipline_path(["extension.py"], environ=environ)
  
file_path: zipline/zipline/utils/paths.py
imports: from errno import EEXIST
  import os
  from os.path import exists, expanduser, join
  import pandas
label_desc: Use image node_id 10 for calling a global function with example usage: default_extension(environ) and returns: zipline_path