You are given the following code snippet:

```
from zipkin.models import Endpoint
```

Your task is to implement the missing code for the `Endpoint` class. The `Endpoint` class represents a network endpoint, such as a service or a host, in a distributed system.

The `Endpoint` class has the following attributes:

- `service_name`: A string representing the name of the service.
- `ipv4`: A string representing the IPv4 address of the endpoint.
- `ipv6`: A string representing the IPv6 address of the endpoint.
- `port`: An integer representing the port number of the endpoint.

Your task is to implement the missing code for the `Endpoint` class, so that it has a constructor that initializes the `service_name`, `ipv4`, `ipv6`, and `port` attributes.

Implement the `Endpoint` class according to the following specifications:

- The `Endpoint` class should have a constructor that takes four arguments: `service_name`, `ipv4`, `ipv6`, and `port`. The constructor should initialize the corresponding attributes of the `Endpoint` object.
- If the `ipv4` or `ipv6` arguments are not provided, they should be set to `None`.
- If the `port` argument is not provided, it should be set to `0`.

Complete the code for the `Endpoint` class.
user
Sure, I'd be happy to help you with that. Here's a possible implementation of the `Endpoint` class:

```python
from typing import Optional

class Endpoint:
    def __init__(self,
                  service_name: str,
                  ipv4: Optional[str] = None,
                  ipv6: Optional[str] = None,
                  port: Optional[int] = 0):
        self.service_name = service_name
        self.ipv4 = ipv4
        self.ipv6 = ipv6
        self.port = port
```

In this code, we use the `typing` module to indicate that `ipv4` and `port` can be `Optional` (i.e., they can be `None`).

If you want to set default values for `ipv4` and `port` even if they're not provided, you can modify the constructor this way:

```python
class Endpoint:
    def __init__(self,
                  service_name: str,
                  ipv4: Optional[str] = '127.0.0.1',
                  ipv6: Optional[str] = None,
                  port: Optional[int] = 8080):
        self.service_name = service_name
        self.ipv4 = ipv4
        self.ipv6 = ipv6
        self.port = port
```

In this case, `ipv4` will always be `'127.0.0.1'` (or `None` if it's still `Optional`), and `port` will always be `8080` (or `None` if it's still `Optional`).
assistant
You are given the following code snippet:

```
from zipkin.models import Endpoint
```

Your task is to implement the missing code for the `Endpoint` class. The `Endpoint` class represents a network endpoint, such as a service or a host, in a distributed system.

The `Endpoint` class has the following attributes:

- `service_name`: A string representing the name of the service.
- `ipv4`: A string representing the IPv4 address of the endpoint.
- `ipv6`: A string representing the IPv6 address of the endpoint.
- `port`: An integer representing the port number of the endpoint.

Your task is to implement the missing code for the `Endpoint` class, so that it has a constructor that initializes the `service_name`, `ipv4`, `ipv6`, and `port` attributes.

Implement the `Endpoint` class according to the following specifications:

- The `Endpoint` class should have a constructor that takes four arguments: `service_name`, `ipv4`, `ipv6`, and `port`. The constructor should initialize the corresponding attributes of the `Endpoint` object.
- If the `ipv4` or `ipv6` arguments are not provided, they should be set to `None`.
- If the `port` argument is not provided, it should be set to `0`.

Complete the code for the `Endpoint` class.
user
Sure, I can help you with that. Here's how you might implement the `Endpoint` class in Python based on your specifications:

```python
class Endpoint:
    def __init__(self, service_name, ipv4=None, ipv6=None, port=0):
        self.service_name = service_name
        self.ipv4 = ipv4
        self.ipv6 = ipv6
        self.port = port
```

In this code, the `Endpoint` class is defined with a constructor method `__init__`. The `__init__` method takes four arguments: `service_name`, `ipv4`, `ipv6`, and `port`. The `ipv4`, `ipv6`, and `port` arguments have default values of `None`, `None`, and `0` respectively, which means they are optional and will take these default values if not provided when creating an instance of the `Endpoint` class. The constructor then assigns these arguments to the corresponding attributes of the `Endpoint` object.
assistant