input: Write a function to generate a voltage signal with random noise using a Python script. The function should take in the frequency and amplitude of the signal as inputs and return the noisy voltage signal.
  assert np.array_equal(generate_noisy_signal(250, 1)[:5], np.sin(2*np.pi*250*np.linspace(0, 1, 1000))[:5] + np.random.normal(0, 0.1, 1000)[:5])
  assert np.array_equal(generate_noisy_signal(500, 2)[:5], np.sin(2*np.pi*500*np.linspace(0, 1, 1000))[:5] + np.random.normal(0, 0.1, 1000)[:5])
  assert np.array_equal(generate_noisy_signal(300, 0.5)[:5], np.sin(2*np.pi*300*np.linspace(0, 1, 1000))[:5] + np.random.normal(0, 0.1, 1000)[:5])
output: def generate_noisy_signal(frequency, amplitude):
      t = np.linspace(0, 1, 1000)
      signal = amplitude * np.sin(2 * np.pi * frequency * t)
      noise = np.random.normal(0, 0.1, 1000)
      return signal + noise