class_docstr: Reader class for 'wav.scp' containing multiple sounds.
  
  This is useful when loading variable numbers of audios for different samples.
  
  Examples:
      wav.scp is a text file that looks like the following:
  
      key1 /some/path/a1.wav /another/path/a2.wav /yet/another/path/a3.wav
      key2 /some/path/b1.wav /another/path/b2.wav
      key3 /some/path/c1.wav /another/path/c2.wav /yet/another/path/c3.wav
      key4 /some/path/d1.wav
      ...
  
      >>> reader = SoundScpReader('wav.scp', stack_axis=0)
      >>> rate, stacked_arrays = reader['key1']
      >>> assert stacked_arrays.shape[0] == 3
  
      Note:
          All audios in each sample must have the same sampling rates.
          Audios of different lengths in each sample will be right-padded with np.nan
              to the same length.
code: def __getitem__(self, key) -> Tuple[int, np.ndarray]:
      wavs = self.data[key]
      arrays, prev_rate = [], None
      for wav in wavs:
          if self.dtype == "float16":
              array, rate = soundfile_read(
                  wav, dtype="float32", always_2d=self.always_2d
              )
              array = array.astype(self.dtype)
          else:
              array, rate = soundfile_read(
                  wav, dtype=self.dtype, always_2d=self.always_2d
              )
          arrays.append(array)
          if prev_rate is not None:
              assert rate == prev_rate, (prev_rate, rate)
          prev_rate = rate
      # Returned as scipy.io.wavread's order
      return rate, self.pad_to_same_length(
          arrays, pad=self.pad, axis=self.stack_axis
      )
  
file_path: espnet/espnet2/fileio/multi_sound_scp.py
imports: import collections.abc
  from typing import Tuple
  import numpy
  from typeguard import check_argument_types
  from espnet2.fileio.read_text import read_multi_columns_text
  from espnet2.fileio.sound_scp import soundfile_read
label_desc: Use image node_id 2 for calling the MultiSoundScpReader obj's underlying member method code with example usage: obj.__getitem__(key) and returns: rate,  self