code: def catalyst_root(environ=None):
      """
      Get the root directory for all catalyst-managed files.
  
      For testing purposes, this accepts a dictionary to interpret as the os
      environment.
  
      Parameters
      ----------
      environ : dict, optional
          A dict to interpret as the os environment.
  
      Returns
      -------
      root : string
          Path to the catalyst root dir.
      """
      if environ is None:
          environ = os.environ
  
      root = environ.get("CATALYST_ROOT", None)
      if root is None:
          root = os.path.join(expanduser("~"), ".catalyst")
  
      return root
  
file_path: catalyst/catalyst/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 8 for calling a global function with example usage: catalyst_root(environ) and returns: root