docs: def vault_file(env, default):
      """The path to a misc Vault file
      This function will check for the env override on a file
      path, compute a fully qualified OS appropriate path to
      the desired file and return it if it exists. Otherwise
      returns None
      """
      home = os.environ['HOME'] if 'HOME' in os.environ else \
          os.environ['USERPROFILE']
      filename = os.environ.get(env, os.path.join(home, default))
      filename = abspath(filename)
      if os.path.exists(filename):
          return filename
  
      return None