input: Write a function to create a command-line application in Python that stores customer data and allows the user to query customers by their name. If the customer name is provided, the function should search for and print customer data. If no name is provided, it should print a message indicating that the customer name is required. The function should be named `print_customer_data` and handle command-line arguments.
  
  assert print_customer_data("John Doe")==None
  assert print_customer_data("Alice Smith")==None
  assert print_customer_data("")==None
  assert print_customer_data("InvalidName")==None
output: def print_customer_data(name):
      customers = {
          "John Doe": "Customer ID: 123, Email: john.doe@example.com",
          "Alice Smith": "Customer ID: 456, Email: alice.smith@example.com"
      }
      if name:
          if name in customers:
              print(customers[name])
          else:
              print("Customer not found.")
      else:
          print("Customer name is required.")