input: Write a python function to plot a bar chart of fruit quantities sold from a given CSV file.
  assert plot_fruit_quantities("fruits.csv") is None
output: def plot_fruit_quantities(csv_file):
      import pandas as pd
      import matplotlib.pyplot as plt
  
      # Read the CSV file into a DataFrame
      df = pd.read_csv(csv_file)
  
      # Assume the CSV has columns 'Fruit' and 'Quantity'
      fruit_quantities = df.groupby('Fruit')['Quantity'].sum()
  
      # Plot the bar chart
      fruit_quantities.plot(kind='bar')
      plt.xlabel('Fruit')
      plt.ylabel('Quantity Sold')
      plt.title('Quantities of Fruits Sold')
      plt.show()