input: Write a python function to plot a histogram using matplotlib for a given data list and number of bins.
  assert plot_histogram([2, 4, 5, 3, 5, 6, 8, 2], 5) == None
  assert plot_histogram([1, 1, 2, 3, 4, 5, 5, 6, 7, 8, 9, 9], 4) == None
output: def plot_histogram(data, bins):
      import matplotlib.pyplot as plt
      
      plt.hist(data, bins=bins)
      plt.xlabel('Data')
      plt.ylabel('Frequency')
      plt.title('Histogram')
      plt.show()