python-stdlib\enum\enum.py: Rewrite Enum with Gemini.

Rewrite Enum with Gemini.
Add enum.md.

Signed-off-by: Ihor Nehrutsa <Ihor.Nehrutsa@gmail.com>

Author: IhorNehrutsa

python-stdlib/enum/enum.md

@@ -0,0 +1,120 @@
+Below is the documentation for your `enum.py` library. This file explains the core concepts of your custom `Enum` implementation and provides practical examples for embedded development and general logic.
+
+---
+
+# Custom Enum Library for Python & MicroPython
+
+This library provides a flexible, memory-efficient `Enum` class designed for dynamic usage and seamless mathematical integration. Unlike the standard CPython `Enum`, this version allows for runtime expansion and direct arithmetic operations without needing to access a `.value` property.
+
+## Core Features
+* **Transparent Math**: Supports arithmetic (`+`, `-`, `*`, `/`) and bitwise (`&`, `|`, `^`, `<<`, `>>`) operations directly on enum members.
+* **Dynamic Expansion**: Add new members at runtime via `.append()` or direct attribute assignment.
+* **Memory Efficient**: Uses `__slots__` in the `ValueWrapper` to minimize RAM usage on platforms like the ESP32.
+* **Flexible Initialization**: Can be initialized via class inheritance, dictionaries, or keyword arguments.
+
+---
+
+## Usage Examples
+
+### 1. Hardware Pin Configuration (ESP32)
+Define your hardware pins using class inheritance. You can skip internal or reserved pins using the `__skipped__` attribute.
+
+```python
+from enum import Enum
+
+class Pins(Enum):
+    # Members defined at class level
+    LED = 2
+    BUTTON = 4
+    # Members to exclude from the enum mapping
+    __skipped__ = ('RESERVED_PIN',)
+    RESERVED_PIN = 0
+
+# You can also add pins during instantiation
+pins = Pins(SDA=21, SCL=22)
+
+print(f"I2C SDA Pin: {pins.SDA}") # Output: 21
+print(f"Is pin 21 valid? {pins.is_value(21)}") # Output: True
+```
+
+### 2. Math and Register Logic
+The `ValueWrapper` allows you to perform calculations directly. This is particularly useful for bitmasks and step-based logic.
+
+```python
+# Initialize with key-value pairs
+brightness = Enum(MIN=0, STEP=25, MAX=255)
+
+# Direct arithmetic (Forward and Reflected)
+next_level = brightness.MIN + brightness.STEP // 2
+complex_math = 100 + brightness.STEP 
+
+print(f"Next Level: {next_level}") # Output: 12
+print(f"Complex Math: {complex_math}") # Output: 125
+
+# Bitwise operations for register control
+flags = Enum(BIT_0=0x01, BIT_1=0x02)
+combined = flags.BIT_0 | flags.BIT_1
+print(f"Combined Flags: {hex(combined)}") # Output: 0x03
+```
+
+### 3. Dynamic State Machines
+You can expand an `Enum` as your program logic progresses, such as adding states to a connection manager.
+
+```python
+status = Enum(IDLE=0, CONNECTING=1)
+
+# Add multiple members via append()
+status.append(CONNECTED=2, ERROR=3)
+
+# Add a single member via direct assignment
+status.DISCONNECTING = 4
+
+for name, val in status.items():
+    print(f"Status {name} has code {val}")
+```
+
+### 4. Working with Different Data Types
+Enums are not restricted to integers; they can wrap strings, floats, and booleans.
+
+```python
+commands = Enum(
+    START="CMD_START",
+    STOP="CMD_STOP",
+    TIMEOUT=5.5,
+    IS_ACTIVE=True
+)
+
+if commands.IS_ACTIVE:
+    # Use str() to get the wrapped string value
+    print(f"Executing: {commands.START}") 
+```
+
+### 5. Introspection and Utilities
+The library provides helper methods to validate values or find keys based on their values.
+
+```python
+class ErrorCodes(Enum):
+    NOT_FOUND = 404
+    SERVER_ERROR = 500
+
+# Check if a value exists in the Enum
+exists = ErrorCodes.is_value(404) # True
+
+# Get the formatted string name from a value
+name = ErrorCodes.key_from_value(500) 
+print(name) # Output: ErrorCodes.SERVER_ERROR
+```
+
+---
+
+## API Reference
+
+### `ValueWrapper`
+The internal class that wraps values to enable mathematical transparency.
+* `.value`: Access the raw value.
+* `()`: Calling the object returns the raw value.
+
+### `Enum` (Inherits from `dict`)
+* `append(arg=None, **kwargs)`: Adds new members to the Enum.
+* `is_value(value)`: Returns `True` if the value exists in the Enum.
+* `key_from_value(value)`: Returns the string representation (e.g., `ClassName.KEY`) for a given value.