class_docstr: Adds an audio backdoor trigger to a set of audio examples. Works for a single example or a batch of examples.
docstr: :param x: N x L matrix or length L array, where N is number of examples, L is the length in number of samples.
            X is in range [-1,1].
  :return: Backdoored audio.
code: def insert(self, x: np.ndarray) -> np.ndarray:
      """
      :param x: N x L matrix or length L array, where N is number of examples, L is the length in number of samples.
                X is in range [-1,1].
      :return: Backdoored audio.
      """
      n_dim = len(x.shape)
      if n_dim == 2:
          return np.array(
              [self.insert(single_audio) for single_audio in x]
          )
      if n_dim != 1:
          raise ValueError("Invalid array shape " + str(x.shape))
      original_dtype = x.dtype
      audio = np.copy(x)
      length = audio.shape[0]
      bd_length = self.trigger.shape[0]
      if bd_length > length:
          raise ValueError(
              "Backdoor audio does not fit inside the original audio."
          )
      if self.random:
          shift = np.random.randint(length - bd_length)
      else:
          shift = self.shift
      if shift + bd_length > length:
          raise ValueError(
              "Shift + Backdoor length is greater than audio's length."
          )
  
      audio[shift : shift + bd_length] += self.scaled_trigger
      audio = np.clip(audio, -1.0, 1.0)
      return audio.astype(original_dtype)
  
file_path: adversarial-robustness-toolbox/art/attacks/poisoning/perturbations/audio_perturbations.py
imports: from typing import Optional
  import librosa
  import numpy
label_desc: Use image node_id 2 for calling the CacheTrigger obj's underlying member method code with example usage: obj.insert(x) and returns: audio, np