input: Write a python function to create a full name for a Customer instance.
  assert create_full_name(customer) == "John Smith"
  assert create_full_name(Customer("Jane", "Doe", "jane.doe@example.com")) == "Jane Doe"
  assert create_full_name(Customer("Alice", "Johnson", "alice.johnson@example.com")) == "Alice Johnson"
output: def create_full_name(customer):
      return f"{customer.first_name} {customer.last_name}"