input: Write a python function to compute the Fast Fourier Transform (FFT) of a given signal and plot its frequency spectrum using matplotlib.
  assert np.allclose(compute_fft(np.sin(2*np.pi*np.linspace(0, 1, 400))), np.fft.fft(np.sin(2*np.pi*np.linspace(0, 1, 400))))
  assert np.allclose(compute_fft(np.cos(2*np.pi*np.linspace(0, 1, 400))), np.fft.fft(np.cos(2*np.pi*np.linspace(0, 1, 400))))
  assert np.allclose(compute_fft(np.sin(5*2*np.pi*np.linspace(0, 1, 400)) + np.cos(10*2*np.pi*np.linspace(0, 1, 400))), np.fft.fft(np.sin(5*2*np.pi*np.linspace(0, 1, 400)) + np.cos(10*2*np.pi*np.linspace(0, 1, 400))))
output: import numpy as np
  import matplotlib.pyplot as plt
  
  def compute_fft(signal):
      fft_result = np.fft.fft(signal)
      freqs = np.fft.fftfreq(len(signal))
      plt.plot(freqs, np.abs(fft_result))
      plt.title("Frequency Spectrum")
      plt.xlabel("Frequency")
      plt.ylabel("Amplitude")
      plt.show()
      return fft_result