input: Write a function to create a command-line application in Python that stores customer data and allows customers to query by customer name. The main function should accept a single command-line argument representing the customer name, search for the customer data, and print the results. If no arguments or more than one argument is provided, the function should print an error message. The function should be named print_customer_data and be called from a main block.
  
  assert print_customer_data("John")==None
  assert print_customer_data("Jane")==None
  assert print_customer_data("Alice")==None
  assert print_customer_data("Bob")==None
  assert print_customer_data("")==None
output: def print_customer_data(customer_name):
      if not customer_name:
          print("Error: No customer name provided.")
          return
      customers = {
          "John": "Data for John",
          "Jane": "Data for Jane",
          "Alice": "Data for Alice",
          "Bob": "Data for Bob"
      }
      if customer_name in customers:
          print(customers[customer_name])
      else:
          print(f"No data found for customer: {customer_name}")