------
## 最终结论
```python
def snake_to_camel(snake_str):
    # Split the string by underscores
    words = snake_str.split('_')
    # Capitalize the first letter of each word and join them
    camel_case_str = ''.join(word.capitalize() for word in words)
    return camel_case_str

# Test cases
assert snake_to_camel('python_program') == 'PythonProgram'
assert snake_to_camel('python_language') == 'PythonLanguage'
assert snake_to_camel('programming_language') == 'ProgrammingLanguage'
```