input: Write a python function to plot a graph using matplotlib given two lists X and Y.
  assert plot_graph([2,4,6,8,10], [5,10,15,20,25]) == None
  assert plot_graph([1,2,3], [4,5,6]) == None
output: def plot_graph(X, Y):
      import matplotlib.pyplot as plt
  
      plt.plot(X, Y)
      plt.xlabel('X-axis')
      plt.ylabel('Y-axis')
      plt.title('Plot of X vs Y')
      plt.grid(True)
      plt.show()