<s>[INST] Here is some code for a basic chatbot in Python:
```
class ChatBot:
    def __init__(self, name):
        self.name = name
        self.handler = self

    def handle(self, command):
        return "{0} don't understand {1}".format(self.name, command)
```
I want to modify the code so that if the `handle` method is called with a command that starts with the prefix "@", I can register a custom handler for it. To do this, I would like to add a `register_prefix` method that takes a prefix and a handler function as arguments. If a command starts with the prefix "@custom", for example, the chatbot should call the custom handler function "custom".

How can I do this?

Here are some example use cases:
```
chatbot = ChatBot("BasicBot")
def custom_handler(command):
    return "You called custom handler!"

chatbot.register_prefix("@custom", custom_handler)
print(chatbot.handle("@custom Hello!"))[/INST]