input: Write a function to generate a voltage signal with random noise given a signal frequency and amplitude. The generated signal should be a sine wave with the specified frequency and amplitude, perturbed by normally distributed noise.
  
  def generate_voltage_signal(freq, amplitude):
      t = np.linspace(0, 1, 1000)
      voltage_signal = np.sin(2*np.pi*freq*t) + np.random.normal(0, 0.1, 1000)
      return voltage_signal
  
  assert np.allclose(generate_voltage_signal(250, 1)[0], np.sin(2*np.pi*250*0) + np.random.normal(0, 0.1))
  assert np.allclose(generate_voltage_signal(250, 1)[1], np.sin(2*np.pi*250*0.001) + np.random.normal(0, 0.1))
  assert np.allclose(generate_voltage_signal(250, 1)[999], np.sin(2*np.pi*250*0.999) + np.random.normal(0, 0.1))
output: 
  def generate_voltage_signal(freq, amplitude):
      t = np.linspace(0, 1, 1000)
      voltage_signal = amplitude * np.sin(2*np.pi*freq*t) + np.random.normal(0, 0.1, 1000)
      return voltage_signal
  