input: Write a python function to create a Customer class and test its methods.
  assert c1.get_name() == "John Doe"
  assert c1.get_address() == "123 Elm Street"
  assert c1.get_phone() == "555-1234"
  assert c2.get_name() == "Jane Smith"
  assert c2.get_address() == "456 Oak Avenue"
  assert c2.get_phone() == "555-5678"
  c1.set_name("Johnny Doe")
  assert c1.get_name() == "Johnny Doe"
  c2.set_address("789 Pine Road")
  assert c2.get_address() == "789 Pine Road"
output: def create_customer_class():
      class Customer:
          def __init__(self, name, address, phone):
              self._name = name
              self._address = address
              self._phone = phone
  
          def get_name(self):
              return self._name
  
          def get_address(self):
              return self._address
  
          def get_phone(self):
              return self._phone
  
          def set_name(self, name):
              self._name = name
  
          def set_address(self, address):
              self._address = address
  
          def set_phone(self, phone):
              self._phone = phone
      
      return Customer
  
  Customer = create_customer_class()
  c1 = Customer("John Doe", "123 Elm Street", "555-1234")
  c2 = Customer("Jane Smith", "456 Oak Avenue", "555-5678")
  
  assert c1.get_name() == "John Doe"
  assert c1.get_address() == "123 Elm Street"
  assert c1.get_phone() == "555-1234"
  assert c2.get_name() == "Jane Smith"
  assert c2.get_address() == "456 Oak Avenue"
  assert c2.get_phone() == "555-5678"
  c1.set_name("Johnny Doe")
  assert c1.get_name() == "Johnny Doe"
  c2.set_address("789 Pine Road")
  assert c2.get_address() == "789 Pine Road"