added style guide

.tinycoder/rules/python_style_guide.md

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+# Python Style Guide
+
+## Code Style and Organization
+
+- **PEP 8 Compliance**: Follow PEP-8 with 4-space indentation
+- **Naming Conventions**:
+  - `snake_case` for functions, variables, and methods
+  - `PascalCase` for classes
+  - `UPPER_SNAKE_CASE` for constants
+  - `_leading_underscore` for private attributes/methods
+
+## Writing Clean Code
+
+- **Type Hints**: Always use type hints for function parameters and return values
+- **Docstrings**: Use Google-style docstrings with clear sections
+- **String Formatting**: Use f-strings for clarity and performance
+- **Resource Management**: Always use context managers for files and resources
+- **Comments**: Use comments to explain "why" not "what", don't state the obvious
+
+## Error Handling
+
+- Use specific exception types, not just `except Exception:`
+- Handle exceptions where you can take meaningful action
+- Validate input early to avoid deep error handling
+
+## Avoid Common Pitfalls
+
+- Mutable default arguments: `def func(arg=[]): # Dangerous!`
+- Deep nesting: Refactor code with more than 3 levels of indentation
+- Magic numbers: Use constants or config variables instead
+- Reinventing built-in functionality
+
+Remember: Code is read much more often than it's written. Optimize for readability and maintainability.