code: def generate(self):
      raise NotImplementedError(
          "SignalGenerator subclasses must implement the generate() method, and *should not* call the superclass implementation."
      )
  
imports: import math
  import array
  import itertools
  import random
  from .audio_segment import AudioSegment
  from .utils import db_to_float, get_frame_width, get_array_type, get_min_max_value
label_desc: Use image node_id 3 for calling the SignalGenerator obj's underlying member method code with example usage: obj.generate() without return types