Write a Python function `snake_to_camel` that converts a given snake_case string into a CamelCase string.
#### Requirements:
- The input will be a string in snake_case format (e.g., `"example_string"`).
- The output should be a string in CamelCase format (e.g., `"ExampleString"`).
#### Example Usage:
```python [main.nopy]
print(snake_to_camel("android_tv")) # Output: "AndroidTv"
print(snake_to_camel("google_pixel")) # Output: "GooglePixel"
print(snake_to_camel("apple_watch")) # Output: "AppleWatch"
```
#### Constraints:
- Assume the input string will only contain lowercase letters and underscores.
- The input string will not start or end with an underscore, and there will be no consecutive underscores.