input: Write a python function to plot sales data for two products over 6 months using matplotlib.
  assert plot_sales_data() is None
output: def plot_sales_data():
      import matplotlib.pyplot as plt
  
      months = ['January', 'February', 'March', 'April', 'May', 'June']
      product1_sales = [150, 200, 250, 300, 350, 400]
      product2_sales = [100, 150, 200, 250, 300, 350]
  
      plt.plot(months, product1_sales, label='Product 1', marker='o')
      plt.plot(months, product2_sales, label='Product 2', marker='o')
  
      plt.xlabel('Months')
      plt.ylabel('Sales')
      plt.title('Sales Data for Two Products Over 6 Months')
      plt.legend()
      plt.grid(True)
      plt.show()