1. The changes improve the configurability of the `TextGeneration` struct and its initialization by refactoring generation parameters (`temperature`, `top_p`) to use non-optional types with default values, simplifying their use throughout the codebase.
2. The argument parser is updated to enhance usability: `verbose_prompt` is renamed to a more general `verbose` flag, several arguments are given default values (e.g., `temperature`, `top_p`, `sample_len`), and optional arguments like `cache_path` and `weight_path` are now properly handled with conditional logic and fallbacks.
3. The code loading the model configuration is updated to support deserializing from a JSON config file using Serde, and the `Config` struct is extended with a new `rope_ratio` field with a default value via a helper function, improving flexibility for different model setups.
4. Import statements and general code layout are cleaned up for clarity and consistency, including reorganizing imports and removing unnecessary unwraps or panics, while maintaining the same core functionality of the text generation pipeline.