The conversation between human and AI assistant.
How do I determine if a string has all unique characters?
That makes sense. Is there any other way to do this?
Yes, you could also do it using a dictionary. Here's the code for that:
```
def is_unique(string):
    char_counts = {}
    for char in string:
        if char in char_counts:
            return False
        char_counts[char] = 1
    return True
```