code: def from_folder(cls, folder: str) -> 'TrainData':
          
          return cls(find_wavs(folder), find_wavs(join(folder, 'test')))
docs: Load a set of data from a structured folder in the following format:
          {prefix}/
              wake-word/
                  *.wav
              not-wake-word/
                  *.wav
              test/
                  wake-word/
                      *.wav
                  not-wake-word/
                      *.wav