docs: def cables_from_source(path, predicate=None):
      """\
      Returns a generator with ``ICable`` instances.
  
      `path`
          Either a directory or a CSV file.
      `predicate`
          A predicate that is invoked for each cable reference identifier.
          If the predicate evaluates to ``False`` the cable is ignored.
          By default, all cables are used.
          I.e. ``cables_from_source('cables.csv', lambda r: r.startswith('09'))``
          would return cables where the reference identifier starts with ``09``.
      """
      return cables_from_directory(path, predicate) if os.path.isdir(path) else cables_from_csv(path, predicate)