code: def get_directories(
          self, directory: str = None, packages: typing.List[str] = None
      ) -> typing.List[str]:
          
          directories = []
          if directory is not None:
              directories.append(directory)
  
          for package in packages or []:
              spec = importlib.util.find_spec(package)
              assert spec is not None, f"Package {package!r} could not be found."
              assert (
                  spec.origin is not None
              ), "Directory 'statics' in package {package!r} could not be found."
              directory = os.path.normpath(os.path.join(spec.origin, "..", "statics"))
              assert os.path.isdir(
                  directory
              ), "Directory 'statics' in package {package!r} could not be found."
              directories.append(directory)
  
          return directories
docs: Given `directory` and `packages` arugments, return a list of all the
          directories that should be used for serving static files from.