Enhance functions Documentation and Improve Error Messages

[Faisal-Alsrheed]

Description

• While reviewing the API documentation for Google's Generative AI Python API, I noticed that several functions were missing docstrings, while others required improvements to enhance clarity and understanding.
• While trying the API, I also noticed that there is room to enhance error feedback for better debugging and developer guidance.

Proposed Changes:

1. Added Missing Docstrings:

   • Introduced docstrings for previously undocumented functions to enhance the completeness of API documentation.

2. Enhanced Existing Docstrings:

   • Updated and detailed existing docstrings to improve clarity and the understanding of API functions.

3. Improved Error Messages:

   • Refined error messages to be more descriptive, aiding in quicker debugging and resolution.

Changed files

1. google/generativeai/answer.py - 13 changes (6 additions & 7 deletions)
2. google/generativeai/client.py - 10 changes (7 additions & 3 deletions)
3. google/generativeai/discuss.py - 34 changes (21 additions & 13 deletions)
4. google/generativeai/embedding.py - 11 changes (6 additions & 5 deletions)
5. google/generativeai/files.py - 5 changes (4 additions & 1 deletion)
6. google/generativeai/generative_models.py - 48 changes (25 additions & 23 deletions)
7. google/generativeai/models.py - 48 changes (29 additions & 19 deletions)
8. google/generativeai/operations.py - 8 changes (6 additions & 2 deletions)
9. google/generativeai/permission.py - 8 changes (3 additions & 5 deletions)
10. google/generativeai/responder.py - 12 changes (6 additions & 6 deletions)
11. google/generativeai/retriever.py - 16 changes (6 additions & 10 deletions)
12. google/generativeai/text.py - 8 changes (6 additions & 2 deletions)
13. google/generativeai/types/content_types.py - 85 changes (50 additions & 35 deletions)
14. google/generativeai/types/file_types.py - 6 changes (5 additions & 1 deletion)
15. google/generativeai/types/generation_types.py - 33 changes (14 additions & 19 deletions)
16. google/generativeai/types/helper_types.py - 5 changes (4 additions & 1 deletion)
17. google/generativeai/types/model_types.py - 18 changes (14 additions & 4 deletions)
18. google/generativeai/types/permission_types.py - 9 changes (4 additions & 5 deletions)
19. google/generativeai/types/retriever_types.py - 63 changes (38 additions & 25 deletions)
20. google/generativeai/utils.py - 2 changes (2 additions & 0 deletions)
21. tests/test_client.py - 2 changes (1 addition & 1 deletion)

Checklist

• [x] Code formatted with Black
• [x] All tests passing with pytest
• [x] Documentation successfully built with build_docs.py