input: def generate_voltage_signal(frequency: int, amplitude: float) -> np.ndarray:
      """ Generate a voltage signal with random noise. The signal has a specific frequency 
      and amplitude. The time duration is set to 1 second, with 1000 samples.
      >>> generate_voltage_signal(250, 1)
      array([1.02345678, 0.98765432, ..., -1.01234567])
      """
      t = np.linspace(0, 1, 1000)
      voltage_signal = np.sin(2 * np.pi * frequency * t) + np.random.normal(0, 0.1, 1000)
      return voltage_signal
output:     t = np.linspace(0, 1, 1000)
      voltage_signal = amplitude * np.sin(2 * np.pi * frequency * t) + np.random.normal(0, 0.1, 1000)
      return voltage_signal