input: 
  def generate_voltage_signal(frequency: int, amplitude: float, noise_std: float, time_samples: int) -> np.ndarray:
      """ Generate a voltage signal with specified frequency, amplitude, and added random noise.
      The signal is generated over a time period from 0 to 1 second.
      >>> generate_voltage_signal(250, 1, 0.1, 1000)
      array([0.90705627, 0.63661072, 0.73886205, ..., 0.14081981, 0.91165945, 0.87275524])
      """
      t = np.linspace(0, 1, time_samples)
      return np.sin(2 * np.pi * frequency * t) + np.random.normal(0, noise_std, time_samples)
  
output:     t = np.linspace(0, 1, time_samples)
      signal = amplitude * np.sin(2 * np.pi * frequency * t)
      noise = np.random.normal(0, noise_std, time_samples)
      return signal + noise