input: Write a python function to generate a noisy sine wave signal, given frequency, amplitude, and number of points.
  assert np.allclose(generate_noisy_signal(250, 1, 1000).mean(), 0, atol=0.1)
  assert len(generate_noisy_signal(250, 1, 1000)) == 1000
  assert np.allclose(generate_noisy_signal(250, 1, 1000).std(), 1, atol=0.2)
output: import numpy as np
  
  def generate_noisy_signal(frequency, amplitude, num_points):
      t = np.linspace(0, 1, num_points)
      signal = amplitude * np.sin(2 * np.pi * frequency * t)
      noise = np.random.normal(0, 1, num_points)
      noisy_signal = signal + noise
      return noisy_signal