input: def generate_voltage_signal(frequency: float, amplitude: float, noise_std_dev: float, duration: float, num_samples: int) -> np.ndarray:
      """ Generate a voltage signal with a specified frequency, amplitude, and added random noise.
      The signal is generated over a given duration with a specified number of samples.
      >>> generate_voltage_signal(250, 1, 0.1, 1, 1000)
      array([ 0.94481953,  0.9577062 ,  0.72365086, ...,  0.79377886,  1.14904033, -0.10414643])
      """
      t = np.linspace(0, duration, num_samples)
      voltage_signal = amplitude * np.sin(2 * np.pi * frequency * t) + np.random.normal(0, noise_std_dev, num_samples)
      return voltage_signal
output:     t = np.linspace(0, duration, num_samples)
      voltage_signal = amplitude * np.sin(2 * np.pi * frequency * t) + np.random.normal(0, noise_std_dev, num_samples)
      return voltage_signal