A solution for Colab exercise

signal2int.py

def signal2int(signal, sample_rate=16_000, seq_length=4):
  """
  Decode a sine wave signal back into digits
  """
  digits = []

  for start_index in range(0, sample_rate * seq_length, sample_rate):
    end_index = start_index + sample_rate - 1

    window_samples = signal[start_index:end_index]
    window_pitch = extract_pitch(window_samples)
    window_digit = int(window_pitch/100 - 1)
    
    digits.append(window_digit)

  return digits